<?xml version="1.0" encoding="UTF-8" ?>
<?xml-stylesheet type="text/xsl" href="https://communities.bentley.com/cfs-file/__key/system/syndication/rss.xsl" media="screen"?><rss version="2.0" xmlns:dc="http://purl.org/dc/elements/1.1/"><channel><title>Tractive Stress (aka Tractive Force, Shear Stress) Calculations and Design</title><link>https://communities.bentley.com/products/hydraulics___hydrology/w/hydraulics_and_hydrology__wiki/20512/tractive-stress-aka-tractive-force-shear-stress-calculations-and-design</link><description /><dc:language>en-US</dc:language><generator>Telligent Community 12</generator><item><title>Tractive Stress (aka Tractive Force, Shear Stress) Calculations and Design</title><link>https://communities.bentley.com/products/hydraulics___hydrology/w/hydraulics_and_hydrology__wiki/20512/tractive-stress-aka-tractive-force-shear-stress-calculations-and-design</link><pubDate>Thu, 06 Oct 2022 13:02:51 GMT</pubDate><guid isPermaLink="false">6dad98f5-dbc9-4c4d-a9ba-e9da8dc6aa8e:c88a6193-17be-4d9c-b7d6-ac347ba5be13</guid><dc:creator>Jesse Dringoli</dc:creator><comments>https://communities.bentley.com/products/hydraulics___hydrology/w/hydraulics_and_hydrology__wiki/20512/tractive-stress-aka-tractive-force-shear-stress-calculations-and-design#comments</comments><description>Current Revision posted to OpenFlows | Water Infrastructure Wiki by Jesse Dringoli on 10/6/2022 1:02:51 PM&lt;br /&gt;
&lt;table style="background-color:#dce5f0;border:0px solid #dce5f0;" border="0"&gt;
&lt;tbody&gt;
&lt;tr&gt;
&lt;td style="text-align:right;"&gt;&lt;strong&gt;&amp;nbsp;&lt;/strong&gt;&lt;/td&gt;
&lt;td style="text-align:right;"&gt;&lt;strong&gt;Product(s):&lt;/strong&gt;&lt;/td&gt;
&lt;td&gt;SewerGEMS,CivilStorm,SewerCAD&lt;/td&gt;
&lt;td&gt;&lt;/td&gt;
&lt;/tr&gt;
&lt;tr&gt;
&lt;td style="text-align:right;"&gt;&lt;strong&gt;&amp;nbsp;&lt;/strong&gt;&lt;/td&gt;
&lt;td style="text-align:right;"&gt;&lt;strong&gt;Version(s):&lt;/strong&gt;&lt;/td&gt;
&lt;td&gt;08.11.XX.XX and later (features vary)&lt;/td&gt;
&lt;td&gt;&lt;/td&gt;
&lt;/tr&gt;
&lt;tr&gt;
&lt;td style="text-align:right;"&gt;&lt;strong&gt;&amp;nbsp;&lt;/strong&gt;&lt;/td&gt;
&lt;td style="text-align:right;"&gt;&lt;strong&gt;Area:&lt;/strong&gt;&lt;/td&gt;
&lt;td&gt;Modeling&lt;/td&gt;
&lt;td&gt;&lt;/td&gt;
&lt;/tr&gt;
&lt;/tbody&gt;
&lt;/table&gt;
&lt;p&gt;&lt;/p&gt;
&lt;h3&gt;Introduction&lt;/h3&gt;
&lt;p&gt;When conduits and channels have sufficient tractive stress they are essentially self-cleaning in that particles will either not settle or they will be re-suspended if they do. To determine if there is sufficient tractive stress in a gravity conduit or channel, it is necessary to compare the actual tractive stress calculated by the model with a target tractive stress required to move particles. The tractive stress does not need to continuously exceed the target tractive stress to be self-cleaning but should exceed the target at least some time during each day.&lt;/p&gt;
&lt;p&gt;Related PowerPoint presentation available for download here:&lt;/p&gt;
&lt;p&gt;&lt;a href="https://communities.bentley.com/cfs-file/__key/communityserver-wikis-components-files/00-00-00-00-32/Tractive-Force.pptx"&gt;communities.bentley.com/.../Tractive-Force.pptx&lt;/a&gt;&lt;/p&gt;
&lt;h3&gt;Solvers&lt;/h3&gt;
&lt;p&gt;Conduit tractive shear stress is now calculated when using the following solvers (versions 10.00.00.40 and later).&lt;/p&gt;
&lt;ul&gt;
&lt;li&gt;GVF-Convex&lt;/li&gt;
&lt;li&gt;Explicit&lt;/li&gt;
&lt;li&gt;Implicit (Dynamic Wave)&lt;/li&gt;
&lt;/ul&gt;
&lt;p style="margin-left:30px;"&gt;Note: Previously (versions 08.11.xx.xx), tractive stress was only supported by the GVF-Convex solver.&lt;/p&gt;
&lt;h3&gt;Tractive Stress Calculations&lt;/h3&gt;
&lt;p&gt;Tractive stress&amp;nbsp;is computed using the equation:&lt;/p&gt;
&lt;p&gt;&lt;span style="font-size:150%;"&gt;&lt;strong&gt;&amp;tau; = &amp;rho;gRS&lt;/strong&gt;&lt;/span&gt;&lt;/p&gt;
&lt;p&gt;Where&lt;/p&gt;
&lt;p&gt;&amp;tau; = tractive shear stress, Pa&lt;br /&gt; &amp;rho; = fluid density, kg/m3&lt;br /&gt; g = acceleration due to gravity, m/s2&lt;br /&gt; R = hydraulic radius, m&lt;br /&gt; S = slope of energy grade line&lt;/p&gt;
&lt;p&gt;Reference: &lt;a href="/products/hydraulics___hydrology/w/hydraulics_and_hydrology__wiki/20499/academic-book-software-licensing-and-solution-guide" rel="noopener noreferrer" target="_blank"&gt;Wastewater Collection System Modeling and Design&lt;/a&gt;, chapter 2.9&lt;br /&gt;&lt;br /&gt;&lt;/p&gt;
&lt;h3&gt;Tractive Stress&lt;span&gt;&amp;nbsp;&lt;/span&gt;Fields&lt;/h3&gt;
&lt;p&gt;The target tractive stress required to have self-cleaning conduits can be specified globally in the calculation option field &amp;quot;Tractive Stress (Global Minimum)&amp;quot;.&lt;/p&gt;
&lt;p&gt;&lt;a href="/cfs-file/__key/communityserver-wikis-components-files/00-00-00-00-32/TractiveStress_2D00_CaculationOptions1.PNG"&gt;&lt;img alt=" " src="/resized-image/__size/940x0/__key/communityserver-wikis-components-files/00-00-00-00-32/TractiveStress_2D00_CaculationOptions1.PNG" /&gt;&lt;/a&gt;&lt;/p&gt;
&lt;p&gt;Local minimums can also be specified on a per-pipe basis and will override the global target. To do this, set the conduit/channel property &amp;quot;Use Local Minimum Stress (Local Minimum)&amp;quot; to True and enter the target value for that individual element into the field &amp;quot;Tractive Stress (Local Minimum)&amp;quot;.&lt;/p&gt;
&lt;p&gt;&lt;a href="/cfs-file/__key/communityserver-wikis-components-files/00-00-00-00-32/TractiveStress_2D00_Properties_2D00_LocalMinimum.png"&gt;&lt;img alt=" " src="/resized-image/__size/940x0/__key/communityserver-wikis-components-files/00-00-00-00-32/TractiveStress_2D00_Properties_2D00_LocalMinimum.png" /&gt;&lt;/a&gt;&lt;/p&gt;
&lt;p&gt;The following results are provided. The model calculates that available tractive stress for each link element and reports if the target value is exceeded for the current time step or at any time step.&lt;/p&gt;
&lt;p&gt;&lt;a href="/cfs-file/__key/communityserver-wikis-components-files/00-00-00-00-32/TractiveStress_2D00_Properties_2D00_Results.png"&gt;&lt;img alt=" " src="/resized-image/__size/940x0/__key/communityserver-wikis-components-files/00-00-00-00-32/TractiveStress_2D00_Properties_2D00_Results.png" /&gt;&lt;/a&gt;&lt;/p&gt;
&lt;p&gt;The flow used by the tractive force calculation is capped at the full flow capacity of the pipe. So if the calculated flow in the conduit is higher than the capacity (i.e., if the pipe is above capacity), the tractive force will be based on the full flow capacity. If the flow is less than the full flow capacity, the tractive force will be based on the actual flow results.&lt;/p&gt;
&lt;h3&gt;Using Tractive Stress as Design Criteria&lt;/h3&gt;
&lt;p&gt;Starting with the release of CONNECT Edition (version 10.00.00.40 and later) tractive stress&amp;nbsp;be included in constraint based design.&lt;/p&gt;
&lt;p&gt;&lt;a href="/cfs-file/__key/communityserver-wikis-components-files/00-00-00-00-32/TractiveStress_2D00_Design.PNG"&gt;&lt;img alt=" " src="/resized-image/__size/940x0/__key/communityserver-wikis-components-files/00-00-00-00-32/TractiveStress_2D00_Design.PNG" /&gt;&lt;/a&gt;&lt;/p&gt;
&lt;p&gt;The tractive stress constraint will not be met if there is a conflict with either the maximum Cover or maximum Velocity constraints.&lt;br /&gt;Similar to other design constraints, there will be warnings if the new tractive stress constraint is not met, these warnings are only shown if the tractive stress design is included in the design process (the &amp;quot;Include Tractive Stress Design&amp;quot; check box is checked).&lt;/p&gt;
&lt;p&gt;&lt;a href="/cfs-file/__key/communityserver-wikis-components-files/00-00-00-00-32/TractiveStress_2D00_UserNotifications.PNG"&gt;&lt;img alt=" " src="/resized-image/__size/940x0/__key/communityserver-wikis-components-files/00-00-00-00-32/TractiveStress_2D00_UserNotifications.PNG" /&gt;&lt;/a&gt;&lt;/p&gt;
&lt;p&gt;Note: Tractive Stress is also referred to as Tractive Force and Shear Stress. While the term &amp;ldquo;Tractive Force&amp;rdquo; is commonly used, the quantity of interest is actually tractive stress which has units of force per unit area parallel to the direction of flow.&lt;/p&gt;
&lt;h3&gt;Viewing Results with Color Coding&lt;/h3&gt;
&lt;p&gt;You can also color code by &amp;quot;tractive stress target exceeded&amp;quot; or &amp;quot;tractive stress target ever exceeded&amp;quot; to visualize:&lt;/p&gt;
&lt;p&gt;&lt;a href="/cfs-file/__key/communityserver-wikis-components-files/00-00-00-00-32/tractivedp.jpg"&gt;&lt;img alt=" " src="/resized-image/__size/940x0/__key/communityserver-wikis-components-files/00-00-00-00-32/tractivedp.jpg" /&gt;&lt;/a&gt;&lt;/p&gt;
&lt;h3&gt;Troubleshooting&lt;/h3&gt;
&lt;p&gt;Solutions to problems related to Tractive Stress are documented here.&lt;/p&gt;
&lt;p&gt;&lt;strong&gt;Tractive stress is negative for a conduit with adverse slope&lt;/strong&gt;&lt;/p&gt;
&lt;p&gt;Due to the negative pipe slope, the calculated tractive stress for a conduit with an uphill (adverse) slope will show as negative. This issue was reported as of version 10.03.04.53. This issue is planned to be addressed in a future version - reference #&amp;nbsp;1002119.&lt;/p&gt;
&lt;h3&gt;See Also&lt;/h3&gt;
&lt;p&gt;Help Article &amp;quot;Tractive Force Design&amp;quot;&lt;/p&gt;&lt;div style="clear:both;"&gt;&lt;/div&gt;

&lt;div style="font-size: 90%;"&gt;Tags: Tractive Force, shear stress, scour, SewerGEMS, SewerCAD, Reviewed2016, CivilStorm, tractive stress&lt;/div&gt;
</description></item><item><title>Tractive Stress (aka Tractive Force, Shear Stress) Calculations and Design</title><link>https://communities.bentley.com/products/hydraulics___hydrology/w/hydraulics_and_hydrology__wiki/20512/tractive-stress-aka-tractive-force-shear-stress-calculations-and-design/revision/11</link><pubDate>Tue, 23 Nov 2021 11:02:51 GMT</pubDate><guid isPermaLink="false">6dad98f5-dbc9-4c4d-a9ba-e9da8dc6aa8e:c88a6193-17be-4d9c-b7d6-ac347ba5be13</guid><dc:creator>Sushma Choure</dc:creator><comments>https://communities.bentley.com/products/hydraulics___hydrology/w/hydraulics_and_hydrology__wiki/20512/tractive-stress-aka-tractive-force-shear-stress-calculations-and-design#comments</comments><description>Revision 11 posted to OpenFlows | Water Infrastructure Wiki by Sushma Choure on 11/23/2021 11:02:51 AM&lt;br /&gt;
&lt;table style="background-color:#dce5f0;border:0px solid #dce5f0;" border="0"&gt;
&lt;tbody&gt;
&lt;tr&gt;
&lt;td style="text-align:right;"&gt;&lt;strong&gt;&amp;nbsp;&lt;/strong&gt;&lt;/td&gt;
&lt;td style="text-align:right;"&gt;&lt;strong&gt;Product(s):&lt;/strong&gt;&lt;/td&gt;
&lt;td&gt;SewerGEMS,CivilStorm,SewerCAD&lt;/td&gt;
&lt;td&gt;&lt;/td&gt;
&lt;/tr&gt;
&lt;tr&gt;
&lt;td style="text-align:right;"&gt;&lt;strong&gt;&amp;nbsp;&lt;/strong&gt;&lt;/td&gt;
&lt;td style="text-align:right;"&gt;&lt;strong&gt;Version(s):&lt;/strong&gt;&lt;/td&gt;
&lt;td&gt;08.11.XX.XX and later (features vary)&lt;/td&gt;
&lt;td&gt;&lt;/td&gt;
&lt;/tr&gt;
&lt;tr&gt;
&lt;td style="text-align:right;"&gt;&lt;strong&gt;&amp;nbsp;&lt;/strong&gt;&lt;/td&gt;
&lt;td style="text-align:right;"&gt;&lt;strong&gt;Area:&lt;/strong&gt;&lt;/td&gt;
&lt;td&gt;Modeling&lt;/td&gt;
&lt;td&gt;&lt;/td&gt;
&lt;/tr&gt;
&lt;/tbody&gt;
&lt;/table&gt;
&lt;p&gt;&lt;/p&gt;
&lt;h3&gt;Introduction&lt;/h3&gt;
&lt;p&gt;When conduits and channels have sufficient tractive stress they are essentially self-cleaning in that particles will either not settle or they will be re-suspended if they do. To determine if there is sufficient tractive stress in a gravity conduit or channel, it is necessary to compare the actual tractive stress calculated by the model with a target tractive stress required to move particles. The tractive stress does not need to continuously exceed the target tractive stress to be self-cleaning but should exceed the target at least some time during each day.&lt;/p&gt;
&lt;p&gt;Related PowerPoint presentation available for download here:&lt;/p&gt;
&lt;p&gt;&lt;a href="https://communities.bentley.com/cfs-file/__key/communityserver-wikis-components-files/00-00-00-00-32/Tractive-Force.pptx"&gt;communities.bentley.com/.../Tractive-Force.pptx&lt;/a&gt;&lt;/p&gt;
&lt;h3&gt;Solvers&lt;/h3&gt;
&lt;p&gt;Conduit tractive shear stress is now calculated when using the following solvers (versions 10.00.00.40 and later).&lt;/p&gt;
&lt;ul&gt;
&lt;li&gt;GVF-Convex&lt;/li&gt;
&lt;li&gt;Explicit&lt;/li&gt;
&lt;li&gt;Implicit (Dynamic Wave)&lt;/li&gt;
&lt;/ul&gt;
&lt;p style="margin-left:30px;"&gt;Note: Previously (versions 08.11.xx.xx), tractive stress was only supported by the GVF-Convex solver.&lt;/p&gt;
&lt;h3&gt;Tractive Stress Calculations&lt;/h3&gt;
&lt;p&gt;Tractive stress&amp;nbsp;is computed using the equation:&lt;/p&gt;
&lt;p&gt;&lt;span style="font-size:150%;"&gt;&lt;strong&gt;&amp;tau; = &amp;rho;gRS&lt;/strong&gt;&lt;/span&gt;&lt;/p&gt;
&lt;p&gt;Where&lt;/p&gt;
&lt;p&gt;&amp;tau; = tractive shear stress, Pa&lt;br /&gt; &amp;rho; = fluid density, kg/m3&lt;br /&gt; g = acceleration due to gravity, m/s2&lt;br /&gt; R = hydraulic radius, m&lt;br /&gt; S = slope of energy grade line&lt;/p&gt;
&lt;p&gt;Reference: &lt;a href="/products/hydraulics___hydrology/w/hydraulics_and_hydrology__wiki/20499/academic-book-software-licensing-and-solution-guide" rel="noopener noreferrer" target="_blank"&gt;Wastewater Collection System Modeling and Design&lt;/a&gt;, chapter 2.9&lt;br /&gt;&lt;br /&gt;&lt;/p&gt;
&lt;h3&gt;Tractive Stress&lt;span&gt;&amp;nbsp;&lt;/span&gt;Fields&lt;/h3&gt;
&lt;p&gt;The target tractive stress required to have self-cleaning conduits can be specified globally in the calculation option field &amp;quot;Tractive Stress (Global Minimum)&amp;quot;.&lt;/p&gt;
&lt;p&gt;&lt;a href="/cfs-file/__key/communityserver-wikis-components-files/00-00-00-00-32/TractiveStress_2D00_CaculationOptions1.PNG"&gt;&lt;img alt=" " src="/resized-image/__size/940x0/__key/communityserver-wikis-components-files/00-00-00-00-32/TractiveStress_2D00_CaculationOptions1.PNG" /&gt;&lt;/a&gt;&lt;/p&gt;
&lt;p&gt;Local minimums can also be specified on a per-pipe basis and will override the global target. To do this, set the conduit/channel property &amp;quot;Use Local Minimum Stress (Local Minimum)&amp;quot; to True and enter the target value for that individual element into the field &amp;quot;Tractive Stress (Local Minimum)&amp;quot;.&lt;/p&gt;
&lt;p&gt;&lt;a href="/cfs-file/__key/communityserver-wikis-components-files/00-00-00-00-32/TractiveStress_2D00_Properties_2D00_LocalMinimum.png"&gt;&lt;img alt=" " src="/resized-image/__size/940x0/__key/communityserver-wikis-components-files/00-00-00-00-32/TractiveStress_2D00_Properties_2D00_LocalMinimum.png" /&gt;&lt;/a&gt;&lt;/p&gt;
&lt;p&gt;The following results are provided. The model calculates that available tractive stress for each link element and reports if the target value is exceeded for the current time step or at any time step.&lt;/p&gt;
&lt;p&gt;&lt;a href="/cfs-file/__key/communityserver-wikis-components-files/00-00-00-00-32/TractiveStress_2D00_Properties_2D00_Results.png"&gt;&lt;img alt=" " src="/resized-image/__size/940x0/__key/communityserver-wikis-components-files/00-00-00-00-32/TractiveStress_2D00_Properties_2D00_Results.png" /&gt;&lt;/a&gt;&lt;/p&gt;
&lt;p&gt;The flow used by the tractive force calculation is capped at the full flow capacity of the pipe. So if the calculated flow in the conduit is higher than the capacity (i.e., if the pipe is above capacity), the tractive force will be based on the full flow capacity. If the flow is less than the full flow capacity, the tractive force will be based on the actual flow results.&lt;/p&gt;
&lt;h3&gt;Using Tractive Stress as Design Criteria&lt;/h3&gt;
&lt;p&gt;Starting with the release of CONNECT Edition (version 10.00.00.40 and later) tractive stress&amp;nbsp;be included in constraint based design.&lt;/p&gt;
&lt;p&gt;&lt;a href="/cfs-file/__key/communityserver-wikis-components-files/00-00-00-00-32/TractiveStress_2D00_Design.PNG"&gt;&lt;img alt=" " src="/resized-image/__size/940x0/__key/communityserver-wikis-components-files/00-00-00-00-32/TractiveStress_2D00_Design.PNG" /&gt;&lt;/a&gt;&lt;/p&gt;
&lt;p&gt;The tractive stress constraint will not be met if there is a conflict with either the maximum Cover or maximum Velocity constraints.&lt;br /&gt;Similar to other design constraints, there will be warnings if the new tractive stress constraint is not met, these warnings are only shown if the tractive stress design is included in the design process (the &amp;quot;Include Tractive Stress Design&amp;quot; check box is checked).&lt;/p&gt;
&lt;p&gt;&lt;a href="/cfs-file/__key/communityserver-wikis-components-files/00-00-00-00-32/TractiveStress_2D00_UserNotifications.PNG"&gt;&lt;img alt=" " src="/resized-image/__size/940x0/__key/communityserver-wikis-components-files/00-00-00-00-32/TractiveStress_2D00_UserNotifications.PNG" /&gt;&lt;/a&gt;&lt;/p&gt;
&lt;p&gt;Note: Tractive Stress is also referred to as Tractive Force and Shear Stress. While the term &amp;ldquo;Tractive Force&amp;rdquo; is commonly used, the quantity of interest is actually tractive stress which has units of force per unit area parallel to the direction of flow.&lt;/p&gt;
&lt;h3&gt;Viewing Results with Color Coding&lt;/h3&gt;
&lt;p&gt;You can also color code by &amp;quot;tractive stress target exceeded&amp;quot; or &amp;quot;tractive stress target ever exceeded&amp;quot; to visualize:&lt;/p&gt;
&lt;p&gt;&lt;a href="/cfs-file/__key/communityserver-wikis-components-files/00-00-00-00-32/tractivedp.jpg"&gt;&lt;img alt=" " src="/resized-image/__size/940x0/__key/communityserver-wikis-components-files/00-00-00-00-32/tractivedp.jpg" /&gt;&lt;/a&gt;&lt;/p&gt;
&lt;h3&gt;See Also&lt;/h3&gt;
&lt;p&gt;Help Article &amp;quot;Tractive Force Design&amp;quot;&lt;/p&gt;&lt;div style="clear:both;"&gt;&lt;/div&gt;

&lt;div style="font-size: 90%;"&gt;Tags: Tractive Force, shear stress, scour, SewerGEMS, SewerCAD, Reviewed2016, CivilStorm, tractive stress&lt;/div&gt;
</description></item><item><title>Tractive Stress (aka Tractive Force, Shear Stress) Calculations and Design</title><link>https://communities.bentley.com/products/hydraulics___hydrology/w/hydraulics_and_hydrology__wiki/20512/tractive-stress-aka-tractive-force-shear-stress-calculations-and-design/revision/10</link><pubDate>Thu, 15 Aug 2019 15:43:43 GMT</pubDate><guid isPermaLink="false">6dad98f5-dbc9-4c4d-a9ba-e9da8dc6aa8e:c88a6193-17be-4d9c-b7d6-ac347ba5be13</guid><dc:creator>Jesse Dringoli</dc:creator><comments>https://communities.bentley.com/products/hydraulics___hydrology/w/hydraulics_and_hydrology__wiki/20512/tractive-stress-aka-tractive-force-shear-stress-calculations-and-design#comments</comments><description>Revision 10 posted to OpenFlows | Water Infrastructure Wiki by Jesse Dringoli on 8/15/2019 3:43:43 PM&lt;br /&gt;
&lt;table style="background-color:#dce5f0;border:0px solid #dce5f0;" border="0"&gt;
&lt;tbody&gt;
&lt;tr&gt;
&lt;td style="text-align:right;"&gt;&lt;strong&gt;&amp;nbsp;&lt;/strong&gt;&lt;/td&gt;
&lt;td style="text-align:right;"&gt;&lt;strong&gt;Product(s):&lt;/strong&gt;&lt;/td&gt;
&lt;td&gt;SewerGEMS,CivilStorm,SewerCAD&lt;/td&gt;
&lt;td&gt;&lt;/td&gt;
&lt;/tr&gt;
&lt;tr&gt;
&lt;td style="text-align:right;"&gt;&lt;strong&gt;&amp;nbsp;&lt;/strong&gt;&lt;/td&gt;
&lt;td style="text-align:right;"&gt;&lt;strong&gt;Version(s):&lt;/strong&gt;&lt;/td&gt;
&lt;td&gt;08.11.XX.XX and later (features vary)&lt;/td&gt;
&lt;td&gt;&lt;/td&gt;
&lt;/tr&gt;
&lt;tr&gt;
&lt;td style="text-align:right;"&gt;&lt;strong&gt;&amp;nbsp;&lt;/strong&gt;&lt;/td&gt;
&lt;td style="text-align:right;"&gt;&lt;strong&gt;Area:&lt;/strong&gt;&lt;/td&gt;
&lt;td&gt;Modeling&lt;/td&gt;
&lt;td&gt;&lt;/td&gt;
&lt;/tr&gt;
&lt;/tbody&gt;
&lt;/table&gt;
&lt;p&gt;&amp;nbsp;&lt;/p&gt;
&lt;h3&gt;Introduction&lt;/h3&gt;
&lt;p&gt;When conduits and channels have sufficient tractive stress they are essentially self-cleaning in that particles will either not settle or they will be re-suspended if they do. To determine if there is sufficient tractive stress in a gravity conduit or channel, it is necessary to compare the actual tractive stress calculated by the model with a target tractive stress required to move particles. The tractive stress does not need to continuously exceed the target tractive stress to be self-cleaning but should exceed the target at least some time during each day.&lt;/p&gt;
&lt;p&gt;Related PowerPoint presentation available for download here:&lt;/p&gt;
&lt;p&gt;&lt;a href="https://communities.bentley.com/cfs-file/__key/communityserver-wikis-components-files/00-00-00-00-32/Tractive-Force.pptx"&gt;communities.bentley.com/.../Tractive-Force.pptx&lt;/a&gt;&lt;/p&gt;
&lt;h3&gt;Solvers&lt;/h3&gt;
&lt;p&gt;Conduit tractive shear stress is now calculated when using the following solvers (versions 10.00.00.40 and later).&lt;/p&gt;
&lt;ul&gt;
&lt;li&gt;GVF-Convex&lt;/li&gt;
&lt;li&gt;Explicit&lt;/li&gt;
&lt;li&gt;Implicit (Dynamic Wave)&lt;/li&gt;
&lt;/ul&gt;
&lt;p style="margin-left:30px;"&gt;Note: Previously (versions 08.11.xx.xx), tractive stress was only supported by the GVF-Convex solver.&lt;/p&gt;
&lt;h3&gt;Tractive Stress Calculations&lt;/h3&gt;
&lt;p&gt;Tractive stress&amp;nbsp;is computed using the equation:&lt;/p&gt;
&lt;p&gt;&lt;span style="font-size:150%;"&gt;&lt;strong&gt;&amp;tau; = &amp;rho;gRS&lt;/strong&gt;&lt;/span&gt;&lt;/p&gt;
&lt;p&gt;Where&lt;/p&gt;
&lt;p&gt;&amp;tau; = tractive shear stress, Pa&lt;br /&gt; &amp;rho; = fluid density, kg/m3&lt;br /&gt; g = acceleration due to gravity, m/s2&lt;br /&gt; R = hydraulic radius, m&lt;br /&gt; S = slope of energy grade line&lt;/p&gt;
&lt;p&gt;Reference: &lt;a href="https://store.bentley.com/en/products/books/9781934493038--Wastewater-Collection-System-Modeling-and-Design"&gt;Wastewater Collection System Modeling and Design&lt;/a&gt;, chapter 2.9&lt;br /&gt;&lt;br /&gt;&lt;/p&gt;
&lt;h3&gt;Tractive Stress&lt;span&gt;&amp;nbsp;&lt;/span&gt;Fields&lt;/h3&gt;
&lt;p&gt;The target tractive stress required to have self-cleaning conduits can be specified globally in the calculation option field &amp;quot;Tractive Stress (Global Minimum)&amp;quot;.&lt;/p&gt;
&lt;p&gt;&lt;a href="/cfs-file/__key/communityserver-wikis-components-files/00-00-00-00-32/TractiveStress_2D00_CaculationOptions1.PNG"&gt;&lt;img alt=" " src="/resized-image/__size/940x0/__key/communityserver-wikis-components-files/00-00-00-00-32/TractiveStress_2D00_CaculationOptions1.PNG" /&gt;&lt;/a&gt;&lt;/p&gt;
&lt;p&gt;Local minimums can also be specified on a per-pipe basis and will override the global target. To do this, set the conduit/channel property &amp;quot;Use Local Minimum Stress (Local Minimum)&amp;quot; to True and enter the target value for that individual element into the field &amp;quot;Tractive Stress (Local Minimum)&amp;quot;.&lt;/p&gt;
&lt;p&gt;&lt;a href="/cfs-file/__key/communityserver-wikis-components-files/00-00-00-00-32/TractiveStress_2D00_Properties_2D00_LocalMinimum.png"&gt;&lt;img alt=" " src="/resized-image/__size/940x0/__key/communityserver-wikis-components-files/00-00-00-00-32/TractiveStress_2D00_Properties_2D00_LocalMinimum.png" /&gt;&lt;/a&gt;&lt;/p&gt;
&lt;p&gt;The following results are provided. The model calculates that available tractive stress for each link element and reports if the target value is exceeded for the current time step or at any time step.&lt;/p&gt;
&lt;p&gt;&lt;a href="/cfs-file/__key/communityserver-wikis-components-files/00-00-00-00-32/TractiveStress_2D00_Properties_2D00_Results.png"&gt;&lt;img alt=" " src="/resized-image/__size/940x0/__key/communityserver-wikis-components-files/00-00-00-00-32/TractiveStress_2D00_Properties_2D00_Results.png" /&gt;&lt;/a&gt;&lt;/p&gt;
&lt;p&gt;The flow used by the tractive force calculation is capped at the full flow capacity of the pipe. So if the calculated flow in the conduit is higher than the capacity (i.e., if the pipe is above capacity), the tractive force will be based on the full flow capacity. If the flow is less than the full flow capacity, the tractive force will be based on the actual flow results.&lt;/p&gt;
&lt;h3&gt;Using Tractive Stress as Design Criteria&lt;/h3&gt;
&lt;p&gt;Starting with the release of CONNECT Edition (version 10.00.00.40 and later) tractive stress&amp;nbsp;be included in constraint based design.&lt;/p&gt;
&lt;p&gt;&lt;a href="/cfs-file/__key/communityserver-wikis-components-files/00-00-00-00-32/TractiveStress_2D00_Design.PNG"&gt;&lt;img alt=" " src="/resized-image/__size/940x0/__key/communityserver-wikis-components-files/00-00-00-00-32/TractiveStress_2D00_Design.PNG" /&gt;&lt;/a&gt;&lt;/p&gt;
&lt;p&gt;The tractive stress constraint will not be met if there is a conflict with either the maximum Cover or maximum Velocity constraints.&lt;br /&gt;Similar to other design constraints, there will be warnings if the new tractive stress constraint is not met, these warnings are only shown if the tractive stress design is included in the design process (the &amp;quot;Include Tractive Stress Design&amp;quot; check box is checked).&lt;/p&gt;
&lt;p&gt;&lt;a href="/cfs-file/__key/communityserver-wikis-components-files/00-00-00-00-32/TractiveStress_2D00_UserNotifications.PNG"&gt;&lt;img alt=" " src="/resized-image/__size/940x0/__key/communityserver-wikis-components-files/00-00-00-00-32/TractiveStress_2D00_UserNotifications.PNG" /&gt;&lt;/a&gt;&lt;/p&gt;
&lt;p&gt;Note: Tractive Stress is also referred to as Tractive Force and Shear Stress. While the term &amp;ldquo;Tractive Force&amp;rdquo; is commonly used, the quantity of interest is actually tractive stress which has units of force per unit area parallel to the direction of flow.&lt;/p&gt;
&lt;h3&gt;Viewing Results with Color Coding&lt;/h3&gt;
&lt;p&gt;You can also color code by &amp;quot;tractive stress target exceeded&amp;quot; or &amp;quot;tractive stress target ever exceeded&amp;quot; to visualize:&lt;/p&gt;
&lt;p&gt;&lt;a href="/cfs-file/__key/communityserver-wikis-components-files/00-00-00-00-32/tractivedp.jpg"&gt;&lt;img alt=" " src="/resized-image/__size/940x0/__key/communityserver-wikis-components-files/00-00-00-00-32/tractivedp.jpg" /&gt;&lt;/a&gt;&lt;/p&gt;
&lt;h3&gt;See Also&lt;/h3&gt;
&lt;p&gt;Help Article &amp;quot;Tractive Force Design&amp;quot;&lt;/p&gt;&lt;div style="clear:both;"&gt;&lt;/div&gt;

&lt;div style="font-size: 90%;"&gt;Tags: Tractive Force, shear stress, scour, SewerGEMS, SewerCAD, Reviewed2016, CivilStorm, tractive stress&lt;/div&gt;
</description></item><item><title>Tractive Stress (aka Tractive Force, Shear Stress) Calculations and Design</title><link>https://communities.bentley.com/products/hydraulics___hydrology/w/hydraulics_and_hydrology__wiki/20512/tractive-stress-aka-tractive-force-shear-stress-calculations-and-design/revision/9</link><pubDate>Thu, 15 Aug 2019 14:49:15 GMT</pubDate><guid isPermaLink="false">6dad98f5-dbc9-4c4d-a9ba-e9da8dc6aa8e:c88a6193-17be-4d9c-b7d6-ac347ba5be13</guid><dc:creator>Jesse Dringoli</dc:creator><comments>https://communities.bentley.com/products/hydraulics___hydrology/w/hydraulics_and_hydrology__wiki/20512/tractive-stress-aka-tractive-force-shear-stress-calculations-and-design#comments</comments><description>Revision 9 posted to OpenFlows | Water Infrastructure Wiki by Jesse Dringoli on 8/15/2019 2:49:15 PM&lt;br /&gt;
&lt;table style="background-color:#dce5f0;border:0px solid #dce5f0;" border="0"&gt;
&lt;tbody&gt;
&lt;tr&gt;
&lt;td style="text-align:right;"&gt;&lt;strong&gt;&amp;nbsp;&lt;/strong&gt;&lt;/td&gt;
&lt;td style="text-align:right;"&gt;&lt;strong&gt;Product(s):&lt;/strong&gt;&lt;/td&gt;
&lt;td&gt;SewerGEMS,CivilStorm,SewerCAD&lt;/td&gt;
&lt;td&gt;&lt;/td&gt;
&lt;/tr&gt;
&lt;tr&gt;
&lt;td style="text-align:right;"&gt;&lt;strong&gt;&amp;nbsp;&lt;/strong&gt;&lt;/td&gt;
&lt;td style="text-align:right;"&gt;&lt;strong&gt;Version(s):&lt;/strong&gt;&lt;/td&gt;
&lt;td&gt;08.11.XX.XX and later (features vary)&lt;/td&gt;
&lt;td&gt;&lt;/td&gt;
&lt;/tr&gt;
&lt;tr&gt;
&lt;td style="text-align:right;"&gt;&lt;strong&gt;&amp;nbsp;&lt;/strong&gt;&lt;/td&gt;
&lt;td style="text-align:right;"&gt;&lt;strong&gt;Area:&lt;/strong&gt;&lt;/td&gt;
&lt;td&gt;Modeling&lt;/td&gt;
&lt;td&gt;&lt;/td&gt;
&lt;/tr&gt;
&lt;/tbody&gt;
&lt;/table&gt;
&lt;p&gt;&amp;nbsp;&lt;/p&gt;
&lt;h3&gt;Introduction&lt;/h3&gt;
&lt;p&gt;When conduits and channels have sufficient tractive stress they are essentially self-cleaning in that particles will either not settle or they will be re-suspended if they do. To determine if there is sufficient tractive stress in a gravity conduit or channel, it is necessary to compare the actual tractive stress calculated by the model with a target tractive stress required to move particles. The tractive stress does not need to continuously exceed the target tractive stress to be self-cleaning but should exceed the target at least some time during each day.&lt;/p&gt;
&lt;h3&gt;Solvers&lt;/h3&gt;
&lt;p&gt;Conduit tractive shear stress is now calculated when using the following solvers (versions 10.00.00.40 and later).&lt;/p&gt;
&lt;ul&gt;
&lt;li&gt;GVF-Convex&lt;/li&gt;
&lt;li&gt;Explicit&lt;/li&gt;
&lt;li&gt;Implicit (Dynamic Wave)&lt;/li&gt;
&lt;/ul&gt;
&lt;p style="margin-left:30px;"&gt;Note: Previously (versions 08.11.xx.xx), tractive stress was only supported by the GVF-Convex solver.&lt;/p&gt;
&lt;h3&gt;Tractive Stress Calculations&lt;/h3&gt;
&lt;p&gt;Tractive stress&amp;nbsp;is computed using the equation:&lt;/p&gt;
&lt;p&gt;&lt;span style="font-size:150%;"&gt;&lt;strong&gt;&amp;tau; = &amp;rho;gRS&lt;/strong&gt;&lt;/span&gt;&lt;/p&gt;
&lt;p&gt;Where&lt;/p&gt;
&lt;p&gt;&amp;tau; = tractive shear stress, Pa&lt;br /&gt; &amp;rho; = fluid density, kg/m3&lt;br /&gt; g = acceleration due to gravity, m/s2&lt;br /&gt; R = hydraulic radius, m&lt;br /&gt; S = slope of energy grade line&lt;/p&gt;
&lt;p&gt;Reference: &lt;a href="https://store.bentley.com/en/products/books/9781934493038--Wastewater-Collection-System-Modeling-and-Design"&gt;Wastewater Collection System Modeling and Design&lt;/a&gt;, chapter 2.9&lt;br /&gt;&lt;br /&gt;&lt;/p&gt;
&lt;h3&gt;Tractive Stress&lt;span&gt;&amp;nbsp;&lt;/span&gt;Fields&lt;/h3&gt;
&lt;p&gt;The target tractive stress required to have self-cleaning conduits can be specified globally in the calculation option field &amp;quot;Tractive Stress (Global Minimum)&amp;quot;.&lt;/p&gt;
&lt;p&gt;&lt;a href="/cfs-file/__key/communityserver-wikis-components-files/00-00-00-00-32/TractiveStress_2D00_CaculationOptions1.PNG"&gt;&lt;img alt=" " src="/resized-image/__size/940x0/__key/communityserver-wikis-components-files/00-00-00-00-32/TractiveStress_2D00_CaculationOptions1.PNG" /&gt;&lt;/a&gt;&lt;/p&gt;
&lt;p&gt;Local minimums can also be specified on a per-pipe basis and will override the global target. To do this, set the conduit/channel property &amp;quot;Use Local Minimum Stress (Local Minimum)&amp;quot; to True and enter the target value for that individual element into the field &amp;quot;Tractive Stress (Local Minimum)&amp;quot;.&lt;/p&gt;
&lt;p&gt;&lt;a href="/cfs-file/__key/communityserver-wikis-components-files/00-00-00-00-32/TractiveStress_2D00_Properties_2D00_LocalMinimum.png"&gt;&lt;img alt=" " src="/resized-image/__size/940x0/__key/communityserver-wikis-components-files/00-00-00-00-32/TractiveStress_2D00_Properties_2D00_LocalMinimum.png" /&gt;&lt;/a&gt;&lt;/p&gt;
&lt;p&gt;The following results are provided. The model calculates that available tractive stress for each link element and reports if the target value is exceeded for the current time step or at any time step.&lt;/p&gt;
&lt;p&gt;&lt;a href="/cfs-file/__key/communityserver-wikis-components-files/00-00-00-00-32/TractiveStress_2D00_Properties_2D00_Results.png"&gt;&lt;img alt=" " src="/resized-image/__size/940x0/__key/communityserver-wikis-components-files/00-00-00-00-32/TractiveStress_2D00_Properties_2D00_Results.png" /&gt;&lt;/a&gt;&lt;/p&gt;
&lt;p&gt;The flow used by the tractive force calculation is capped at the full flow capacity of the pipe. So if the calculated flow in the conduit is higher than the capacity (i.e., if the pipe is above capacity), the tractive force will be based on the full flow capacity. If the flow is less than the full flow capacity, the tractive force will be based on the actual flow results.&lt;/p&gt;
&lt;h3&gt;Using Tractive Stress as Design Criteria&lt;/h3&gt;
&lt;p&gt;Starting with the release of CONNECT Edition (version 10.00.00.40 and later) tractive stress&amp;nbsp;be included in constraint based design.&lt;/p&gt;
&lt;p&gt;&lt;a href="/cfs-file/__key/communityserver-wikis-components-files/00-00-00-00-32/TractiveStress_2D00_Design.PNG"&gt;&lt;img alt=" " src="/resized-image/__size/940x0/__key/communityserver-wikis-components-files/00-00-00-00-32/TractiveStress_2D00_Design.PNG" /&gt;&lt;/a&gt;&lt;/p&gt;
&lt;p&gt;The tractive stress constraint will not be met if there is a conflict with either the maximum Cover or maximum Velocity constraints.&lt;br /&gt;Similar to other design constraints, there will be warnings if the new tractive stress constraint is not met, these warnings are only shown if the tractive stress design is included in the design process (the &amp;quot;Include Tractive Stress Design&amp;quot; check box is checked).&lt;/p&gt;
&lt;p&gt;&lt;a href="/cfs-file/__key/communityserver-wikis-components-files/00-00-00-00-32/TractiveStress_2D00_UserNotifications.PNG"&gt;&lt;img alt=" " src="/resized-image/__size/940x0/__key/communityserver-wikis-components-files/00-00-00-00-32/TractiveStress_2D00_UserNotifications.PNG" /&gt;&lt;/a&gt;&lt;/p&gt;
&lt;p&gt;Note: Tractive Stress is also referred to as Tractive Force and Shear Stress. While the term &amp;ldquo;Tractive Force&amp;rdquo; is commonly used, the quantity of interest is actually tractive stress which has units of force per unit area parallel to the direction of flow.&lt;/p&gt;
&lt;h3&gt;Viewing Results with Color Coding&lt;/h3&gt;
&lt;p&gt;You can also color code by &amp;quot;tractive stress target exceeded&amp;quot; or &amp;quot;tractive stress target ever exceeded&amp;quot; to visualize:&lt;/p&gt;
&lt;p&gt;&lt;a href="/cfs-file/__key/communityserver-wikis-components-files/00-00-00-00-32/tractivedp.jpg"&gt;&lt;img alt=" " src="/resized-image/__size/940x0/__key/communityserver-wikis-components-files/00-00-00-00-32/tractivedp.jpg" /&gt;&lt;/a&gt;&lt;/p&gt;
&lt;h3&gt;See Also&lt;/h3&gt;
&lt;p&gt;Help Article &amp;quot;Tractive Force Design&amp;quot;&lt;/p&gt;&lt;div style="clear:both;"&gt;&lt;/div&gt;

&lt;div style="font-size: 90%;"&gt;Tags: Tractive Force, shear stress, scour, SewerGEMS, SewerCAD, Reviewed2016, CivilStorm, tractive stress&lt;/div&gt;
</description></item><item><title>Tractive Stress (aka Tractive Force, Shear Stress) Calculations and Design</title><link>https://communities.bentley.com/products/hydraulics___hydrology/w/hydraulics_and_hydrology__wiki/20512/tractive-stress-aka-tractive-force-shear-stress-calculations-and-design/revision/8</link><pubDate>Tue, 23 Jan 2018 17:03:40 GMT</pubDate><guid isPermaLink="false">6dad98f5-dbc9-4c4d-a9ba-e9da8dc6aa8e:c88a6193-17be-4d9c-b7d6-ac347ba5be13</guid><dc:creator>Scott Kampa</dc:creator><comments>https://communities.bentley.com/products/hydraulics___hydrology/w/hydraulics_and_hydrology__wiki/20512/tractive-stress-aka-tractive-force-shear-stress-calculations-and-design#comments</comments><description>Revision 8 posted to OpenFlows | Water Infrastructure Wiki by Scott Kampa on 1/23/2018 5:03:40 PM&lt;br /&gt;
&lt;table style="background-color:#dce5f0;border:0px solid #dce5f0;" border="0"&gt;
&lt;tbody&gt;
&lt;tr&gt;
&lt;td style="text-align:right;"&gt;&lt;strong&gt;&amp;nbsp;&lt;/strong&gt;&lt;/td&gt;
&lt;td style="text-align:right;"&gt;&lt;strong&gt;Product(s):&lt;/strong&gt;&lt;/td&gt;
&lt;td&gt;SewerGEMS,CivilStorm,SewerCAD&lt;/td&gt;
&lt;td&gt;&lt;/td&gt;
&lt;/tr&gt;
&lt;tr&gt;
&lt;td style="text-align:right;"&gt;&lt;strong&gt;&amp;nbsp;&lt;/strong&gt;&lt;/td&gt;
&lt;td style="text-align:right;"&gt;&lt;strong&gt;Version(s):&lt;/strong&gt;&lt;/td&gt;
&lt;td&gt;08.11.XX.XX and later (features vary)&lt;/td&gt;
&lt;td&gt;&lt;/td&gt;
&lt;/tr&gt;
&lt;tr&gt;
&lt;td style="text-align:right;"&gt;&lt;strong&gt;&amp;nbsp;&lt;/strong&gt;&lt;/td&gt;
&lt;td style="text-align:right;"&gt;&lt;strong&gt;Area:&lt;/strong&gt;&lt;/td&gt;
&lt;td&gt;Modeling&lt;/td&gt;
&lt;td&gt;&lt;/td&gt;
&lt;/tr&gt;
&lt;/tbody&gt;
&lt;/table&gt;
&lt;p&gt;&amp;nbsp;&lt;/p&gt;
&lt;h3&gt;Introduction&lt;/h3&gt;
&lt;p&gt;When conduits and channels have sufficient tractive stress they are essentially self-cleaning in that particles will either not settle or they will be re-suspended if they do. To determine if there is sufficient tractive stress in a gravity conduit or channel, it is necessary to compare the actual tractive stress calculated by the model with a target tractive stress required to move particles. The tractive stress does not need to continuously exceed the target tractive stress to be self-cleaning but should exceed the target at least some time during each day.&lt;/p&gt;
&lt;h3&gt;Solvers&lt;/h3&gt;
&lt;p&gt;Conduit tractive shear stress is now calculated when using the following solvers (versions 10.00.00.40 and later).&lt;/p&gt;
&lt;ul&gt;
&lt;li&gt;GVF-Convex&lt;/li&gt;
&lt;li&gt;Explicit&lt;/li&gt;
&lt;li&gt;Implicit (Dynamic Wave)&lt;/li&gt;
&lt;/ul&gt;
&lt;p style="margin-left:30px;"&gt;Note: Previously (versions 08.11.xx.xx), tractive stress was only supported by the GVF-Convex solver.&lt;/p&gt;
&lt;h3&gt;Tractive Stress Fields&lt;/h3&gt;
&lt;p&gt;The target tractive stress required to have self-cleaning conduits can be specified globally in the calculation option field &amp;quot;Tractive Stress (Global Minimum)&amp;quot;.&lt;/p&gt;
&lt;p&gt;&lt;a href="/cfs-file/__key/communityserver-wikis-components-files/00-00-00-00-32/TractiveStress_2D00_CaculationOptions1.PNG"&gt;&lt;img alt=" " src="/resized-image/__size/940x0/__key/communityserver-wikis-components-files/00-00-00-00-32/TractiveStress_2D00_CaculationOptions1.PNG" /&gt;&lt;/a&gt;&lt;/p&gt;
&lt;p&gt;Local minimums can also be specified on a per-pipe basis and will override the global target. To do this, set the conduit/channel property &amp;quot;Use Local Minimum Stress (Local Minimum)&amp;quot; to True and enter the target value for that individual element into the field &amp;quot;Tractive Stress (Local Minimum)&amp;quot;.&lt;/p&gt;
&lt;p&gt;&lt;a href="/cfs-file/__key/communityserver-wikis-components-files/00-00-00-00-32/TractiveStress_2D00_Properties_2D00_LocalMinimum.png"&gt;&lt;img alt=" " src="/resized-image/__size/940x0/__key/communityserver-wikis-components-files/00-00-00-00-32/TractiveStress_2D00_Properties_2D00_LocalMinimum.png" /&gt;&lt;/a&gt;&lt;/p&gt;
&lt;p&gt;The following results are provided. The model calculates that available tractive stress for each link element and reports if the target value is exceeded for the current time step or at any time step.&lt;/p&gt;
&lt;p&gt;&lt;a href="/cfs-file/__key/communityserver-wikis-components-files/00-00-00-00-32/TractiveStress_2D00_Properties_2D00_Results.png"&gt;&lt;img alt=" " src="/resized-image/__size/940x0/__key/communityserver-wikis-components-files/00-00-00-00-32/TractiveStress_2D00_Properties_2D00_Results.png" /&gt;&lt;/a&gt;&lt;/p&gt;
&lt;p&gt;The flow used by the tractive force calculation is capped at the full flow capacity of the pipe. So if the calculated flow in the conduit is higher than the capacity (i.e., if the pipe is above capacity), the tractive force will be based on the full flow capacity. If the flow is less than the full flow capacity, the tractive force will be based on the actual flow results.&lt;/p&gt;
&lt;h3&gt;Using Tractive Stress as Design Criteria&lt;/h3&gt;
&lt;p&gt;Starting with the release of CONNECT Edition (version 10.00.00.40 and later) tractive stress&amp;nbsp;be included in constraint based design.&lt;/p&gt;
&lt;p&gt;&lt;a href="/cfs-file/__key/communityserver-wikis-components-files/00-00-00-00-32/TractiveStress_2D00_Design.PNG"&gt;&lt;img alt=" " src="/resized-image/__size/940x0/__key/communityserver-wikis-components-files/00-00-00-00-32/TractiveStress_2D00_Design.PNG" /&gt;&lt;/a&gt;&lt;/p&gt;
&lt;p&gt;The tractive stress constraint will not be met if there is a conflict with either the maximum Cover or maximum Velocity constraints.&lt;br /&gt;Similar to other design constraints, there will be warnings if the new tractive stress constraint is not met, these warnings are only shown if the tractive stress design is included in the design process (the &amp;quot;Include Tractive Stress Design&amp;quot; check box is checked).&lt;/p&gt;
&lt;p&gt;&lt;a href="/cfs-file/__key/communityserver-wikis-components-files/00-00-00-00-32/TractiveStress_2D00_UserNotifications.PNG"&gt;&lt;img alt=" " src="/resized-image/__size/940x0/__key/communityserver-wikis-components-files/00-00-00-00-32/TractiveStress_2D00_UserNotifications.PNG" /&gt;&lt;/a&gt;&lt;/p&gt;
&lt;p&gt;Note: Tractive Stress is also referred to as Tractive Force and Shear Stress. While the term &amp;ldquo;Tractive Force&amp;rdquo; is commonly used, the quantity of interest is actually tractive stress which has units of force per unit area parallel to the direction of flow.&lt;/p&gt;
&lt;h3&gt;Viewing Results with Color Coding&lt;/h3&gt;
&lt;p&gt;You can also color code by &amp;quot;tractive stress target exceeded&amp;quot; or &amp;quot;tractive stress target ever exceeded&amp;quot; to visualize:&lt;/p&gt;
&lt;p&gt;&lt;a href="/cfs-file/__key/communityserver-wikis-components-files/00-00-00-00-32/tractivedp.jpg"&gt;&lt;img alt=" " src="/resized-image/__size/940x0/__key/communityserver-wikis-components-files/00-00-00-00-32/tractivedp.jpg" /&gt;&lt;/a&gt;&lt;/p&gt;
&lt;h3&gt;See Also&lt;/h3&gt;
&lt;p&gt;Help Article &amp;quot;Tractive Force Design&amp;quot;&lt;/p&gt;&lt;div style="clear:both;"&gt;&lt;/div&gt;

&lt;div style="font-size: 90%;"&gt;Tags: Tractive Force, shear stress, scour, SewerGEMS, SewerCAD, Reviewed2016, CivilStorm, tractive stress&lt;/div&gt;
</description></item><item><title>Tractive Stress (aka Tractive Force, Shear Stress) Calculations and Design</title><link>https://communities.bentley.com/products/hydraulics___hydrology/w/hydraulics_and_hydrology__wiki/20512/tractive-stress-aka-tractive-force-shear-stress-calculations-and-design/revision/7</link><pubDate>Mon, 12 Dec 2016 22:24:46 GMT</pubDate><guid isPermaLink="false">6dad98f5-dbc9-4c4d-a9ba-e9da8dc6aa8e:c88a6193-17be-4d9c-b7d6-ac347ba5be13</guid><dc:creator>Craig Calvin</dc:creator><comments>https://communities.bentley.com/products/hydraulics___hydrology/w/hydraulics_and_hydrology__wiki/20512/tractive-stress-aka-tractive-force-shear-stress-calculations-and-design#comments</comments><description>Revision 7 posted to OpenFlows | Water Infrastructure Wiki by Craig Calvin on 12/12/2016 10:24:46 PM&lt;br /&gt;
&lt;p style="padding:0;margin:0;"&gt;&lt;/p&gt;
&lt;table style="border:0px solid #dce5f0;background-color:#dce5f0;" border="0"&gt;
&lt;tbody&gt;
&lt;tr&gt;
&lt;td style="text-align:right;"&gt;&lt;strong&gt;&amp;nbsp;&lt;/strong&gt;&lt;/td&gt;
&lt;td style="text-align:right;"&gt;&lt;strong&gt;Product(s):&lt;/strong&gt;&lt;/td&gt;
&lt;td&gt;SewerGEMS,CivilStorm,SewerCAD&lt;/td&gt;
&lt;td&gt;&lt;/td&gt;
&lt;/tr&gt;
&lt;tr&gt;
&lt;td style="text-align:right;"&gt;&lt;strong&gt;&amp;nbsp;&lt;/strong&gt;&lt;/td&gt;
&lt;td style="text-align:right;"&gt;&lt;strong&gt;Version(s):&lt;/strong&gt;&lt;/td&gt;
&lt;td&gt;08.11.XX.XX and later (features vary)&lt;/td&gt;
&lt;td&gt;&lt;/td&gt;
&lt;/tr&gt;
&lt;tr&gt;
&lt;td style="text-align:right;"&gt;&lt;strong&gt;&amp;nbsp;&lt;/strong&gt;&lt;/td&gt;
&lt;td style="text-align:right;"&gt;&lt;strong&gt;Area:&lt;/strong&gt;&lt;/td&gt;
&lt;td&gt;Modeling&lt;/td&gt;
&lt;td&gt;&lt;/td&gt;
&lt;/tr&gt;
&lt;/tbody&gt;
&lt;/table&gt;
&lt;p&gt;&amp;nbsp;&lt;/p&gt;
&lt;h3&gt;Introduction&lt;/h3&gt;
&lt;p&gt;When conduits and channels have sufficient tractive stress they are essentially self-cleaning in that particles will either not settle or they will be re-suspended if they do. To determine if there is sufficient tractive stress in a gravity conduit or channel, it is necessary to compare the actual tractive stress calculated by the model with a target tractive stress required to move particles. The tractive stress does not need to continuously exceed the target tractive stress to be self-cleaning but should exceed the target at least some time during each day.&lt;/p&gt;
&lt;h3&gt;Solvers&lt;/h3&gt;
&lt;p&gt;Conduit tractive shear stress is now calculated when using the following solvers (versions 10.00.00.40 and later).&lt;/p&gt;
&lt;ul&gt;
&lt;li&gt;GVF-Convex&lt;/li&gt;
&lt;li&gt;Explicit&lt;/li&gt;
&lt;li&gt;Implicit (Dynamic Wave)&lt;/li&gt;
&lt;/ul&gt;
&lt;p style="margin-left:30px;"&gt;Note: Previously (versions 08.11.xx.xx), tractive stress was only supported by the GVF-Convex solver.&lt;/p&gt;
&lt;h3&gt;Tractive Stress Fields&lt;/h3&gt;
&lt;p&gt;The target tractive stress required to have self-cleaning conduits can be specified globally in the calculation option field &amp;quot;Tractive Stress (Global Minimum)&amp;quot;.&lt;/p&gt;
&lt;p&gt;&lt;a href="/cfs-file/__key/communityserver-wikis-components-files/00-00-00-00-32/TractiveStress_2D00_CaculationOptions1.PNG"&gt;&lt;img alt=" " src="/resized-image/__size/940x0/__key/communityserver-wikis-components-files/00-00-00-00-32/TractiveStress_2D00_CaculationOptions1.PNG" /&gt;&lt;/a&gt;&lt;/p&gt;
&lt;p&gt;Local minimums can also be specified on a per-pipe basis and will override the global target. To do this, set the conduit/channel property &amp;quot;Use Local Minimum Stress (Local Minimum)&amp;quot; to True and enter the target value for that individual element into the field &amp;quot;Tractive Stress (Local Minimum)&amp;quot;.&lt;/p&gt;
&lt;p&gt;&lt;a href="/cfs-file/__key/communityserver-wikis-components-files/00-00-00-00-32/TractiveStress_2D00_Properties_2D00_LocalMinimum.png"&gt;&lt;img alt=" " src="/resized-image/__size/940x0/__key/communityserver-wikis-components-files/00-00-00-00-32/TractiveStress_2D00_Properties_2D00_LocalMinimum.png" /&gt;&lt;/a&gt;&lt;/p&gt;
&lt;p&gt;The following results are provided. The model calculates that available tractive stress for each link element and reports if the target value is exceeded for the current time step or at any time step.&lt;/p&gt;
&lt;p&gt;&lt;a href="/cfs-file/__key/communityserver-wikis-components-files/00-00-00-00-32/TractiveStress_2D00_Properties_2D00_Results.png"&gt;&lt;img alt=" " src="/resized-image/__size/940x0/__key/communityserver-wikis-components-files/00-00-00-00-32/TractiveStress_2D00_Properties_2D00_Results.png" /&gt;&lt;/a&gt;&lt;/p&gt;
&lt;h3&gt;Using Tractive Stress as Design Criteria&lt;/h3&gt;
&lt;p&gt;Starting with the release of CONNECT Edition (version 10.00.00.40 and later) tractive stress&amp;nbsp;be included in constraint based design.&lt;/p&gt;
&lt;p&gt;&lt;a href="/cfs-file/__key/communityserver-wikis-components-files/00-00-00-00-32/TractiveStress_2D00_Design.PNG"&gt;&lt;img alt=" " src="/resized-image/__size/940x0/__key/communityserver-wikis-components-files/00-00-00-00-32/TractiveStress_2D00_Design.PNG" /&gt;&lt;/a&gt;&lt;/p&gt;
&lt;p&gt;The tractive stress constraint will not be met if there is a conflict with either the maximum Cover or maximum Velocity constraints.&lt;br /&gt;Similar to other design constraints, there will be warnings if the new tractive stress constraint is not met, these warnings are only shown if the tractive stress design is included in the design process (the &amp;quot;Include Tractive Stress Design&amp;quot; check box is checked).&lt;/p&gt;
&lt;p&gt;&lt;a href="/cfs-file/__key/communityserver-wikis-components-files/00-00-00-00-32/TractiveStress_2D00_UserNotifications.PNG"&gt;&lt;img alt=" " src="/resized-image/__size/940x0/__key/communityserver-wikis-components-files/00-00-00-00-32/TractiveStress_2D00_UserNotifications.PNG" /&gt;&lt;/a&gt;&lt;/p&gt;
&lt;p&gt;Note: Tractive Stress is also referred to as Tractive Force and Shear Stress. While the term &amp;ldquo;Tractive Force&amp;rdquo; is commonly used, the quantity of interest is actually tractive stress which has units of force per unit area parallel to the direction of flow.&lt;/p&gt;
&lt;h3&gt;Viewing Results with Color Coding&lt;/h3&gt;
&lt;p&gt;You can also color code by &amp;quot;tractive stress target exceeded&amp;quot; or &amp;quot;tractive stress target ever exceeded&amp;quot; to visualize:&lt;/p&gt;
&lt;p&gt;&lt;a href="/cfs-file/__key/communityserver-wikis-components-files/00-00-00-00-32/tractivedp.jpg"&gt;&lt;img alt=" " src="/resized-image/__size/940x0/__key/communityserver-wikis-components-files/00-00-00-00-32/tractivedp.jpg" /&gt;&lt;/a&gt;&lt;/p&gt;
&lt;h3&gt;See Also&lt;/h3&gt;
&lt;p&gt;Help Article &amp;quot;Tractive Force Design&amp;quot;&lt;/p&gt;&lt;div style="clear:both;"&gt;&lt;/div&gt;

&lt;div style="font-size: 90%;"&gt;Tags: Tractive Force, shear stress, scour, SewerGEMS, SewerCAD, Reviewed2016, CivilStorm, tractive stress&lt;/div&gt;
</description></item><item><title>Tractive Stress (aka Tractive Force, Shear Stress) Calculations and Design</title><link>https://communities.bentley.com/products/hydraulics___hydrology/w/hydraulics_and_hydrology__wiki/20512/tractive-stress-aka-tractive-force-shear-stress-calculations-and-design/revision/6</link><pubDate>Mon, 12 Dec 2016 22:24:07 GMT</pubDate><guid isPermaLink="false">6dad98f5-dbc9-4c4d-a9ba-e9da8dc6aa8e:c88a6193-17be-4d9c-b7d6-ac347ba5be13</guid><dc:creator>Craig Calvin</dc:creator><comments>https://communities.bentley.com/products/hydraulics___hydrology/w/hydraulics_and_hydrology__wiki/20512/tractive-stress-aka-tractive-force-shear-stress-calculations-and-design#comments</comments><description>Revision 6 posted to OpenFlows | Water Infrastructure Wiki by Craig Calvin on 12/12/2016 10:24:07 PM&lt;br /&gt;
&lt;p style="padding:0;margin:0;"&gt;&lt;/p&gt;
&lt;table style="border:0px solid #dce5f0;background-color:#dce5f0;" border="0"&gt;
&lt;tbody&gt;
&lt;tr&gt;
&lt;td style="text-align:right;"&gt;&lt;strong&gt;&amp;nbsp;&lt;/strong&gt;&lt;/td&gt;
&lt;td style="text-align:right;"&gt;&lt;strong&gt;Product(s):&lt;/strong&gt;&lt;/td&gt;
&lt;td&gt;SewerGEMS,CivilStorm,SewerCAD&lt;/td&gt;
&lt;td&gt;&lt;/td&gt;
&lt;/tr&gt;
&lt;tr&gt;
&lt;td style="text-align:right;"&gt;&lt;strong&gt;&amp;nbsp;&lt;/strong&gt;&lt;/td&gt;
&lt;td style="text-align:right;"&gt;&lt;strong&gt;Version(s):&lt;/strong&gt;&lt;/td&gt;
&lt;td&gt;08.11.XX.XX and later (features vary)&lt;/td&gt;
&lt;td&gt;&lt;/td&gt;
&lt;/tr&gt;
&lt;tr&gt;
&lt;td style="text-align:right;"&gt;&lt;strong&gt;&amp;nbsp;&lt;/strong&gt;&lt;/td&gt;
&lt;td style="text-align:right;"&gt;&lt;strong&gt;Area:&lt;/strong&gt;&lt;/td&gt;
&lt;td&gt;Modeling&lt;/td&gt;
&lt;td&gt;&lt;/td&gt;
&lt;/tr&gt;
&lt;/tbody&gt;
&lt;/table&gt;
&lt;p&gt;&amp;nbsp;&lt;/p&gt;
&lt;h3&gt;Introduction&lt;/h3&gt;
&lt;p&gt;When conduits and channels have sufficient tractive stress they are essentially self-cleaning in that particles will either not settle or they will be re-suspended if they do. To determine if there is sufficient tractive stress in a gravity conduit or channel, it is necessary to compare the actual tractive stress calculated by the model with a target tractive stress required to move particles. The tractive stress does not need to continuously exceed the target tractive stress to be self-cleaning but should exceed the target at least some time during each day.&lt;/p&gt;
&lt;h3&gt;Solvers&lt;/h3&gt;
&lt;p&gt;Conduit tractive shear stress is now calculated when using the following solvers (versions 10.00.00.40 and later).&lt;/p&gt;
&lt;ul&gt;
&lt;li&gt;GVF-Convex&lt;/li&gt;
&lt;li&gt;Explicit&lt;/li&gt;
&lt;li&gt;Implicit (Dynamic Wave)&lt;/li&gt;
&lt;/ul&gt;
&lt;p style="margin-left:30px;"&gt;Note: Previously (versions 08.11.xx.xx), tractive stress was only supported by the GVF-Convex solver.&lt;/p&gt;
&lt;h3&gt;Tractive Stress Fields&lt;/h3&gt;
&lt;p&gt;The target tractive stress required to have self-cleaning conduits can be specified globally in the calculation option field &amp;quot;Tractive Stress (Global Minimum)&amp;quot;.&lt;/p&gt;
&lt;p&gt;&lt;a href="/cfs-file/__key/communityserver-wikis-components-files/00-00-00-00-32/TractiveStress_2D00_CaculationOptions1.PNG"&gt;&lt;img alt=" " src="/resized-image/__size/940x0/__key/communityserver-wikis-components-files/00-00-00-00-32/TractiveStress_2D00_CaculationOptions1.PNG" /&gt;&lt;/a&gt;&lt;/p&gt;
&lt;p&gt;Local minimums can also be specified on a per-pipe basis and will override the global target. To do this, set the conduit/channel property &amp;quot;Use Local Minimum Stress (Local Minimum)&amp;quot; to True and enter the target value for that individual element into the field &amp;quot;Tractive Stress (Local Minimum)&amp;quot;.&lt;/p&gt;
&lt;p&gt;&lt;a href="/cfs-file/__key/communityserver-wikis-components-files/00-00-00-00-32/TractiveStress_2D00_Properties_2D00_LocalMinimum.png"&gt;&lt;img alt=" " src="/resized-image/__size/940x0/__key/communityserver-wikis-components-files/00-00-00-00-32/TractiveStress_2D00_Properties_2D00_LocalMinimum.png" /&gt;&lt;/a&gt;&lt;/p&gt;
&lt;p&gt;The following results are provided. The model calculates that available tractive stress for each link element and reports if the target value is exceeded for the current time step or at any time step.&lt;/p&gt;
&lt;p&gt;&lt;a href="/cfs-file/__key/communityserver-wikis-components-files/00-00-00-00-32/TractiveStress_2D00_Properties_2D00_Results.png"&gt;&lt;img alt=" " src="/resized-image/__size/940x0/__key/communityserver-wikis-components-files/00-00-00-00-32/TractiveStress_2D00_Properties_2D00_Results.png" /&gt;&lt;/a&gt;&lt;/p&gt;
&lt;h3&gt;Using Tractive Stress as Design Criteria&lt;/h3&gt;
&lt;p&gt;Starting with the release of CONNECT Edition (version 10.00.00.40 and later) tractive stress&amp;nbsp;be included in constraint based design.&lt;/p&gt;
&lt;p&gt;&lt;a href="/cfs-file/__key/communityserver-wikis-components-files/00-00-00-00-32/TractiveStress_2D00_Design.PNG"&gt;&lt;img alt=" " src="/resized-image/__size/940x0/__key/communityserver-wikis-components-files/00-00-00-00-32/TractiveStress_2D00_Design.PNG" /&gt;&lt;/a&gt;&lt;/p&gt;
&lt;p&gt;The tractive stress constraint will not be met if there is a conflict with either the maximum Cover or maximum Velocity constraints.&lt;br /&gt;Similar to other design constraints, there will be warnings if the new tractive stress constraint is not met, these warnings are only shown if the tractive stress design is included in the design process (the &amp;quot;Include Tractive Stress Design&amp;quot; check box is checked).&lt;/p&gt;
&lt;p&gt;&lt;a href="/cfs-file/__key/communityserver-wikis-components-files/00-00-00-00-32/TractiveStress_2D00_UserNotifications.PNG"&gt;&lt;img alt=" " src="/resized-image/__size/940x0/__key/communityserver-wikis-components-files/00-00-00-00-32/TractiveStress_2D00_UserNotifications.PNG" /&gt;&lt;/a&gt;&lt;/p&gt;
&lt;p&gt;Note: Tractive Stress is also referred to as Tractive Force and Shear Stress. While the term &amp;ldquo;Tractive Force&amp;rdquo; is commonly used, the quantity of interest is actually tractive stress which has units of force per unit area parallel to the direction of flow.&lt;/p&gt;
&lt;h3&gt;Viewing Results with Color Coding&lt;/h3&gt;
&lt;p&gt;You can also color code by &amp;quot;tractive stress target exceeded&amp;quot; or &amp;quot;tractive stress target ever exceeded&amp;quot; to visualize:&lt;/p&gt;
&lt;p&gt;&lt;a href="/cfs-file/__key/communityserver-wikis-components-files/00-00-00-00-32/tractivedp.jpg"&gt;&lt;img alt=" " src="/resized-image/__size/940x0/__key/communityserver-wikis-components-files/00-00-00-00-32/tractivedp.jpg" /&gt;&lt;/a&gt;&lt;/p&gt;
&lt;h3&gt;See Also&lt;/h3&gt;
&lt;p&gt;Help Article &amp;quot;Tractive Force Design&amp;quot;&lt;/p&gt;
&lt;p&gt;&lt;/p&gt;
&lt;p&gt;&lt;img width="189" height="60" style="border-width:0px;" alt=" " src="/cfs-file.ashx/__key/communityserver-components-sitefiles/TSG-Logo.png" /&gt;&lt;/p&gt;
&lt;table style="border:0px solid #dce5f0;background-color:#dce5f0;" border="0"&gt;
&lt;tbody&gt;
&lt;tr&gt;
&lt;td style="text-align:right;"&gt;&lt;strong&gt;&amp;nbsp;&lt;/strong&gt;&lt;/td&gt;
&lt;td style="text-align:right;"&gt;&lt;strong&gt;Original Author:&lt;/strong&gt;&lt;/td&gt;
&lt;td&gt;Mark Pachlhofer&lt;/td&gt;
&lt;td&gt;&lt;/td&gt;
&lt;/tr&gt;
&lt;/tbody&gt;
&lt;/table&gt;&lt;div style="clear:both;"&gt;&lt;/div&gt;

&lt;div style="font-size: 90%;"&gt;Tags: Tractive Force, shear stress, scour, SewerGEMS, SewerCAD, Reviewed2016, CivilStorm, tractive stress&lt;/div&gt;
</description></item><item><title>Tractive Stress (aka Tractive Force, Shear Stress) Calculations and Design</title><link>https://communities.bentley.com/products/hydraulics___hydrology/w/hydraulics_and_hydrology__wiki/20512/tractive-stress-aka-tractive-force-shear-stress-calculations-and-design/revision/5</link><pubDate>Mon, 22 Aug 2016 15:34:48 GMT</pubDate><guid isPermaLink="false">6dad98f5-dbc9-4c4d-a9ba-e9da8dc6aa8e:c88a6193-17be-4d9c-b7d6-ac347ba5be13</guid><dc:creator>Craig Calvin</dc:creator><comments>https://communities.bentley.com/products/hydraulics___hydrology/w/hydraulics_and_hydrology__wiki/20512/tractive-stress-aka-tractive-force-shear-stress-calculations-and-design#comments</comments><description>Revision 5 posted to OpenFlows | Water Infrastructure Wiki by Craig Calvin on 8/22/2016 3:34:48 PM&lt;br /&gt;
&lt;p style="padding:0;margin:0;"&gt;&lt;/p&gt;
&lt;table style="border:0px solid #dce5f0;background-color:#dce5f0;" border="0"&gt;
&lt;tbody&gt;
&lt;tr&gt;
&lt;td style="text-align:right;"&gt;&lt;strong&gt;&amp;nbsp;&lt;/strong&gt;&lt;/td&gt;
&lt;td style="text-align:right;"&gt;&lt;strong&gt;Product(s):&lt;/strong&gt;&lt;/td&gt;
&lt;td&gt;SewerGEMS,CivilStorm,SewerCAD&lt;/td&gt;
&lt;td&gt;&lt;/td&gt;
&lt;/tr&gt;
&lt;tr&gt;
&lt;td style="text-align:right;"&gt;&lt;strong&gt;&amp;nbsp;&lt;/strong&gt;&lt;/td&gt;
&lt;td style="text-align:right;"&gt;&lt;strong&gt;Version(s):&lt;/strong&gt;&lt;/td&gt;
&lt;td&gt;08.11.XX.XX and later (features vary)&lt;/td&gt;
&lt;td&gt;&lt;/td&gt;
&lt;/tr&gt;
&lt;tr&gt;
&lt;td style="text-align:right;"&gt;&lt;strong&gt;&amp;nbsp;&lt;/strong&gt;&lt;/td&gt;
&lt;td style="text-align:right;"&gt;&lt;strong&gt;Environment:&lt;/strong&gt;&lt;/td&gt;
&lt;td&gt;N\A&lt;/td&gt;
&lt;td&gt;&lt;/td&gt;
&lt;/tr&gt;
&lt;tr&gt;
&lt;td style="text-align:right;"&gt;&lt;strong&gt;&amp;nbsp;&lt;/strong&gt;&lt;/td&gt;
&lt;td style="text-align:right;"&gt;&lt;strong&gt;Area:&lt;/strong&gt;&lt;/td&gt;
&lt;td&gt;Modeling&lt;/td&gt;
&lt;td&gt;&lt;/td&gt;
&lt;/tr&gt;
&lt;/tbody&gt;
&lt;/table&gt;
&lt;p&gt;&amp;nbsp;&lt;/p&gt;
&lt;h3&gt;Introduction&lt;/h3&gt;
&lt;p&gt;When conduits and channels have sufficient tractive stress they are essentially self-cleaning in that particles will either not settle or they will be re-suspended if they do. To determine if there is sufficient tractive stress in a gravity conduit or channel, it is necessary to compare the actual tractive stress calculated by the model with a target tractive stress required to move particles. The tractive stress does not need to continuously exceed the target tractive stress to be self-cleaning but should exceed the target at least some time during each day.&lt;/p&gt;
&lt;h3&gt;Solvers&lt;/h3&gt;
&lt;p&gt;Conduit tractive shear stress is now calculated when using the following solvers (versions 10.00.00.40 and later).&lt;/p&gt;
&lt;ul&gt;
&lt;li&gt;GVF-Convex&lt;/li&gt;
&lt;li&gt;Explicit&lt;/li&gt;
&lt;li&gt;Implicit (Dynamic Wave)&lt;/li&gt;
&lt;/ul&gt;
&lt;p style="margin-left:30px;"&gt;Note: Previously (versions 08.11.xx.xx), tractive stress was only supported by the GVF-Convex solver.&lt;/p&gt;
&lt;h3&gt;Tractive Stress Fields&lt;/h3&gt;
&lt;p&gt;The target tractive stress required to have self-cleaning conduits can be specified globally in the calculation option field &amp;quot;Tractive Stress (Global Minimum)&amp;quot;.&lt;/p&gt;
&lt;p&gt;&lt;a href="/cfs-file/__key/communityserver-wikis-components-files/00-00-00-00-32/TractiveStress_2D00_CaculationOptions1.PNG"&gt;&lt;img src="/resized-image/__size/940x0/__key/communityserver-wikis-components-files/00-00-00-00-32/TractiveStress_2D00_CaculationOptions1.PNG" alt=" " /&gt;&lt;/a&gt;&lt;/p&gt;
&lt;p&gt;Local minimums can also be specified on a per-pipe basis and will override the global target. To do this, set the conduit/channel property &amp;quot;Use Local Minimum Stress (Local Minimum)&amp;quot; to True and enter the target value for that individual element into the field &amp;quot;Tractive Stress (Local Minimum)&amp;quot;.&lt;/p&gt;
&lt;p&gt;&lt;a href="/cfs-file/__key/communityserver-wikis-components-files/00-00-00-00-32/TractiveStress_2D00_Properties_2D00_LocalMinimum.png"&gt;&lt;img src="/resized-image/__size/940x0/__key/communityserver-wikis-components-files/00-00-00-00-32/TractiveStress_2D00_Properties_2D00_LocalMinimum.png" alt=" " /&gt;&lt;/a&gt;&lt;/p&gt;
&lt;p&gt;The following results are provided. The model calculates that available tractive stress for each link element and reports if the target value is exceeded for the current time step or at any time step.&lt;/p&gt;
&lt;p&gt;&lt;a href="/cfs-file/__key/communityserver-wikis-components-files/00-00-00-00-32/TractiveStress_2D00_Properties_2D00_Results.png"&gt;&lt;img src="/resized-image/__size/940x0/__key/communityserver-wikis-components-files/00-00-00-00-32/TractiveStress_2D00_Properties_2D00_Results.png" alt=" " /&gt;&lt;/a&gt;&lt;/p&gt;
&lt;h3&gt;Using Tractive Stress as Design Criteria&lt;/h3&gt;
&lt;p&gt;Tractive Stress can now also be included in constraint based design.&lt;/p&gt;
&lt;p&gt;&lt;a href="/cfs-file/__key/communityserver-wikis-components-files/00-00-00-00-32/TractiveStress_2D00_Design.PNG"&gt;&lt;img src="/resized-image/__size/940x0/__key/communityserver-wikis-components-files/00-00-00-00-32/TractiveStress_2D00_Design.PNG" alt=" " /&gt;&lt;/a&gt;&lt;/p&gt;
&lt;p&gt;The tractive stress constraint will not be met if there is a conflict with either the maximum Cover or maximum Velocity constraints.&lt;br /&gt;Similar to other design constraints, there will be warnings if the new tractive stress constraint is not met, these warnings are only shown if the tractive stress design is included in the design process (the &amp;quot;Include Tractive Stress Design&amp;quot; check box is checked).&lt;/p&gt;
&lt;p&gt;&lt;a href="/cfs-file/__key/communityserver-wikis-components-files/00-00-00-00-32/TractiveStress_2D00_UserNotifications.PNG"&gt;&lt;img src="/resized-image/__size/940x0/__key/communityserver-wikis-components-files/00-00-00-00-32/TractiveStress_2D00_UserNotifications.PNG" alt=" " /&gt;&lt;/a&gt;&lt;/p&gt;
&lt;p&gt;Note: Tractive Stress is also referred to as Tractive Force and Shear Stress. While the term &amp;ldquo;Tractive Force&amp;rdquo; is commonly used, the quantity of interest is actually tractive stress which has units of force per unit area parallel to the direction of flow.&lt;/p&gt;
&lt;h3&gt;Viewing Results with Color Coding&lt;/h3&gt;
&lt;p&gt;You can also color code by &amp;quot;tractive stress target exceeded&amp;quot; or &amp;quot;tractive stress target ever exceeded&amp;quot; to visualize:&lt;/p&gt;
&lt;p&gt;&lt;a href="/cfs-file/__key/communityserver-wikis-components-files/00-00-00-00-32/tractivedp.jpg"&gt;&lt;img alt=" " src="/resized-image/__size/940x0/__key/communityserver-wikis-components-files/00-00-00-00-32/tractivedp.jpg" /&gt;&lt;/a&gt;&lt;/p&gt;
&lt;h3&gt;See Also&lt;/h3&gt;
&lt;p&gt;Help Article &amp;quot;Tractive Force Design&amp;quot;&lt;/p&gt;
&lt;p&gt;&lt;/p&gt;
&lt;p&gt;&lt;img width="189" height="60" style="border-width:0px;" alt=" " src="/cfs-file.ashx/__key/communityserver-components-sitefiles/TSG-Logo.png" /&gt;&lt;/p&gt;
&lt;table style="border:0px solid #dce5f0;background-color:#dce5f0;" border="0"&gt;
&lt;tbody&gt;
&lt;tr&gt;
&lt;td style="text-align:right;"&gt;&lt;strong&gt;&amp;nbsp;&lt;/strong&gt;&lt;/td&gt;
&lt;td style="text-align:right;"&gt;&lt;strong&gt;Original Author:&lt;/strong&gt;&lt;/td&gt;
&lt;td&gt;Mark Pachlhofer&lt;/td&gt;
&lt;td&gt;&lt;/td&gt;
&lt;/tr&gt;
&lt;/tbody&gt;
&lt;/table&gt;&lt;div style="clear:both;"&gt;&lt;/div&gt;

&lt;div style="font-size: 90%;"&gt;Tags: Tractive Force, shear stress, scour, SewerGEMS, SewerCAD, Reviewed2016, CivilStorm, tractive stress&lt;/div&gt;
</description></item><item><title>How do I set a minimum shear stress to ensure the tractive forces are large enough to scour the pipes?</title><link>https://communities.bentley.com/products/hydraulics___hydrology/w/hydraulics_and_hydrology__wiki/20512/tractive-stress-aka-tractive-force-shear-stress-calculations-and-design/revision/4</link><pubDate>Tue, 19 Jan 2016 19:04:42 GMT</pubDate><guid isPermaLink="false">6dad98f5-dbc9-4c4d-a9ba-e9da8dc6aa8e:c88a6193-17be-4d9c-b7d6-ac347ba5be13</guid><dc:creator>MPachlhofer</dc:creator><comments>https://communities.bentley.com/products/hydraulics___hydrology/w/hydraulics_and_hydrology__wiki/20512/tractive-stress-aka-tractive-force-shear-stress-calculations-and-design#comments</comments><description>Revision 4 posted to OpenFlows | Water Infrastructure Wiki by MPachlhofer on 1/19/2016 7:04:42 PM&lt;br /&gt;
&lt;h1&gt;&lt;b&gt;&lt;img width="189" height="60" style="border-width:0px;" alt=" " src="/Other/Old_Site_Files/Bentley_Folders/m/support/17560/download.aspx" /&gt;&lt;/b&gt;&lt;/h1&gt;
&lt;table align="left" style="border:0px solid #dce5f0;width:500px;background-color:#dce5f0;" border="0"&gt;
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&lt;td style="text-align:right;"&gt;&lt;b&gt;&amp;nbsp;&lt;/b&gt;&lt;/td&gt;
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&lt;/tr&gt;
&lt;tr&gt;
&lt;td style="text-align:right;"&gt;&lt;b&gt;&amp;nbsp;&lt;/b&gt;&lt;/td&gt;
&lt;td style="text-align:right;"&gt;&lt;span style="font-size:medium;"&gt;&lt;b&gt;Applies To&amp;nbsp;&lt;/b&gt;&lt;/span&gt;&lt;/td&gt;
&lt;td&gt;&lt;/td&gt;
&lt;td&gt;&lt;/td&gt;
&lt;/tr&gt;
&lt;tr&gt;
&lt;td style="text-align:right;"&gt;&lt;strong&gt;&amp;nbsp;&lt;/strong&gt;&lt;/td&gt;
&lt;td style="text-align:right;"&gt;&lt;strong&gt;&amp;nbsp;&lt;/strong&gt;&lt;/td&gt;
&lt;td&gt;&lt;/td&gt;
&lt;td&gt;&lt;/td&gt;
&lt;/tr&gt;
&lt;tr&gt;
&lt;td style="text-align:right;"&gt;&lt;strong&gt;&amp;nbsp;&lt;/strong&gt;&lt;/td&gt;
&lt;td style="text-align:right;"&gt;&lt;strong&gt;Product(s):&lt;/strong&gt;&lt;/td&gt;
&lt;td&gt;Bentley SewerGEMS, Bentley SewerCAD&lt;/td&gt;
&lt;td&gt;&lt;/td&gt;
&lt;/tr&gt;
&lt;tr&gt;
&lt;td style="text-align:right;"&gt;&lt;strong&gt;&amp;nbsp;&lt;/strong&gt;&lt;/td&gt;
&lt;td style="text-align:right;"&gt;&lt;strong&gt;Version(s):&lt;/strong&gt;&lt;/td&gt;
&lt;td&gt;08.11.XX.XX&lt;/td&gt;
&lt;td&gt;&lt;/td&gt;
&lt;/tr&gt;
&lt;tr&gt;
&lt;td style="text-align:right;"&gt;&lt;strong&gt;&amp;nbsp;&lt;/strong&gt;&lt;/td&gt;
&lt;td style="text-align:right;"&gt;&lt;strong&gt;Environment:&amp;nbsp;&lt;/strong&gt;&lt;/td&gt;
&lt;td&gt;N/A&lt;/td&gt;
&lt;td&gt;&lt;/td&gt;
&lt;/tr&gt;
&lt;tr&gt;
&lt;td style="text-align:right;"&gt;&lt;strong&gt;&amp;nbsp;&lt;/strong&gt;&lt;/td&gt;
&lt;td style="text-align:right;"&gt;&lt;strong&gt;Area:&amp;nbsp;&lt;/strong&gt;&lt;/td&gt;
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&lt;td&gt;&lt;/td&gt;
&lt;/tr&gt;
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&lt;td style="text-align:right;"&gt;&lt;strong&gt;&amp;nbsp;&lt;/strong&gt;&lt;/td&gt;
&lt;td style="text-align:right;"&gt;&lt;strong&gt;Original Author:&lt;/strong&gt;&lt;/td&gt;
&lt;td&gt;Mark Pachlhofer, Bentley Technical Support Group&lt;/td&gt;
&lt;td&gt;&lt;/td&gt;
&lt;/tr&gt;
&lt;tr&gt;
&lt;td style="text-align:right;"&gt;&lt;strong&gt;&amp;nbsp;&lt;/strong&gt;&lt;/td&gt;
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&lt;td&gt;&lt;/td&gt;
&lt;td&gt;&lt;/td&gt;
&lt;/tr&gt;
&lt;/tbody&gt;
&lt;/table&gt;
&lt;h1&gt;Problem&lt;/h1&gt;
&lt;p&gt;How do I set a minimum shear stress to ensure the tractive forces are large enough to scour the pipes?&lt;/p&gt;
&lt;p&gt;&lt;em&gt;Note: This only applies in SewerGEMS if you are using the GVF Convex Solver&lt;/em&gt;&lt;/p&gt;
&lt;h1&gt;Solution&lt;/h1&gt;
&lt;p&gt;You can set this in the calculation options in the location shown below&lt;/p&gt;
&lt;p&gt;&lt;a href="/cfs-file/__key/communityserver-wikis-components-files/00-00-00-00-32/calcoptions.jpg"&gt;&lt;img alt=" " src="/resized-image/__size/940x0/__key/communityserver-wikis-components-files/00-00-00-00-32/calcoptions.jpg" /&gt;&lt;/a&gt;&lt;/p&gt;
&lt;p&gt;&lt;/p&gt;
&lt;p&gt;You can also specify local tractive stress on a per-pipe basis:&lt;/p&gt;
&lt;p&gt;&lt;a href="/cfs-file/__key/communityserver-wikis-components-files/00-00-00-00-32/tractive_5F00_pg.jpg"&gt;&lt;img alt=" " src="/resized-image/__size/940x0/__key/communityserver-wikis-components-files/00-00-00-00-32/tractive_5F00_pg.jpg" /&gt;&lt;/a&gt;&lt;/p&gt;
&lt;p&gt;&lt;/p&gt;
&lt;p&gt;Then, after computing the model (GVF Convex Solver), you can see the calculated tractive stress and whether or not it met the target. These results are found in the properties of the conduit under the &amp;quot;Results (Tractive Stress)&amp;quot; section or in a Flextable.&lt;/p&gt;
&lt;p&gt;&lt;a href="/cfs-file/__key/communityserver-wikis-components-files/00-00-00-00-32/tractive_5F00_results.jpg"&gt;&lt;img alt=" " src="/resized-image/__size/940x0/__key/communityserver-wikis-components-files/00-00-00-00-32/tractive_5F00_results.jpg" /&gt;&lt;/a&gt;&lt;/p&gt;
&lt;p&gt;&lt;/p&gt;
&lt;p&gt;You can also color code by &amp;quot;tractive stress target exceeded&amp;quot; or &amp;quot;tractive stress target ever exceeded&amp;quot; to visualize:&lt;/p&gt;
&lt;p&gt;&lt;a href="/cfs-file/__key/communityserver-wikis-components-files/00-00-00-00-32/tractivedp.jpg"&gt;&lt;img alt=" " src="/resized-image/__size/940x0/__key/communityserver-wikis-components-files/00-00-00-00-32/tractivedp.jpg" /&gt;&lt;/a&gt;&lt;/p&gt;
&lt;p&gt;&lt;/p&gt;&lt;div style="clear:both;"&gt;&lt;/div&gt;

&lt;div style="font-size: 90%;"&gt;Tags: Tractive Force, shear stress, scour&lt;/div&gt;
</description></item><item><title>How do I set a minimum shear stress to ensure the tractive forces are large enough to scour the pipes?</title><link>https://communities.bentley.com/products/hydraulics___hydrology/w/hydraulics_and_hydrology__wiki/20512/tractive-stress-aka-tractive-force-shear-stress-calculations-and-design/revision/3</link><pubDate>Fri, 15 Jan 2016 17:53:16 GMT</pubDate><guid isPermaLink="false">6dad98f5-dbc9-4c4d-a9ba-e9da8dc6aa8e:c88a6193-17be-4d9c-b7d6-ac347ba5be13</guid><dc:creator>Jesse Dringoli</dc:creator><comments>https://communities.bentley.com/products/hydraulics___hydrology/w/hydraulics_and_hydrology__wiki/20512/tractive-stress-aka-tractive-force-shear-stress-calculations-and-design#comments</comments><description>Revision 3 posted to OpenFlows | Water Infrastructure Wiki by Jesse Dringoli on 1/15/2016 5:53:16 PM&lt;br /&gt;
&lt;h1&gt;&lt;b&gt;&lt;img width="189" height="60" style="border-width:0px;" alt=" " src="/Other/Old_Site_Files/Bentley_Folders/m/support/17560/download.aspx" /&gt;&lt;/b&gt;&lt;/h1&gt;
&lt;table align="left" style="border:0px solid #dce5f0;width:500px;background-color:#dce5f0;" border="0"&gt;
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&lt;td style="text-align:right;"&gt;&lt;b&gt;&amp;nbsp;&lt;/b&gt;&lt;/td&gt;
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&lt;td style="text-align:right;"&gt;&lt;b&gt;&amp;nbsp;&lt;/b&gt;&lt;/td&gt;
&lt;td style="text-align:right;"&gt;&lt;span style="font-size:medium;"&gt;&lt;b&gt;Applies To&amp;nbsp;&lt;/b&gt;&lt;/span&gt;&lt;/td&gt;
&lt;td&gt;&lt;/td&gt;
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&lt;td style="text-align:right;"&gt;&lt;strong&gt;&amp;nbsp;&lt;/strong&gt;&lt;/td&gt;
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&lt;/tr&gt;
&lt;tr&gt;
&lt;td style="text-align:right;"&gt;&lt;strong&gt;&amp;nbsp;&lt;/strong&gt;&lt;/td&gt;
&lt;td style="text-align:right;"&gt;&lt;strong&gt;Product(s):&lt;/strong&gt;&lt;/td&gt;
&lt;td&gt;Bentley SewerGEMS, Bentley SewerCAD&lt;/td&gt;
&lt;td&gt;&lt;/td&gt;
&lt;/tr&gt;
&lt;tr&gt;
&lt;td style="text-align:right;"&gt;&lt;strong&gt;&amp;nbsp;&lt;/strong&gt;&lt;/td&gt;
&lt;td style="text-align:right;"&gt;&lt;strong&gt;Version(s):&lt;/strong&gt;&lt;/td&gt;
&lt;td&gt;08.11.XX.XX&lt;/td&gt;
&lt;td&gt;&lt;/td&gt;
&lt;/tr&gt;
&lt;tr&gt;
&lt;td style="text-align:right;"&gt;&lt;strong&gt;&amp;nbsp;&lt;/strong&gt;&lt;/td&gt;
&lt;td style="text-align:right;"&gt;&lt;strong&gt;Environment:&amp;nbsp;&lt;/strong&gt;&lt;/td&gt;
&lt;td&gt;N/A&lt;/td&gt;
&lt;td&gt;&lt;/td&gt;
&lt;/tr&gt;
&lt;tr&gt;
&lt;td style="text-align:right;"&gt;&lt;strong&gt;&amp;nbsp;&lt;/strong&gt;&lt;/td&gt;
&lt;td style="text-align:right;"&gt;&lt;strong&gt;Area:&amp;nbsp;&lt;/strong&gt;&lt;/td&gt;
&lt;td&gt;&lt;/td&gt;
&lt;td&gt;&lt;/td&gt;
&lt;/tr&gt;
&lt;tr&gt;
&lt;td style="text-align:right;"&gt;&lt;strong&gt;&amp;nbsp;&lt;/strong&gt;&lt;/td&gt;
&lt;td style="text-align:right;"&gt;&lt;strong&gt;Original Author:&lt;/strong&gt;&lt;/td&gt;
&lt;td&gt;Mark Pachlhofer, Bentley Technical Support Group&lt;/td&gt;
&lt;td&gt;&lt;/td&gt;
&lt;/tr&gt;
&lt;tr&gt;
&lt;td style="text-align:right;"&gt;&lt;strong&gt;&amp;nbsp;&lt;/strong&gt;&lt;/td&gt;
&lt;td style="text-align:right;"&gt;&lt;strong&gt;&amp;nbsp;&lt;/strong&gt;&lt;/td&gt;
&lt;td&gt;&lt;/td&gt;
&lt;td&gt;&lt;/td&gt;
&lt;/tr&gt;
&lt;/tbody&gt;
&lt;/table&gt;
&lt;h1&gt;Problem&lt;/h1&gt;
&lt;p&gt;How do I set a minimum shear stress to ensure the tractive forces are large enough to scour the pipes?&lt;/p&gt;
&lt;p&gt;&lt;em&gt;Note: This only applies in SewerGEMS if you are using the GVF Convex Solver&lt;/em&gt;&lt;/p&gt;
&lt;h1&gt;Solution&lt;/h1&gt;
&lt;p&gt;You can set this in the calculation options in the location shown below&lt;/p&gt;
&lt;p&gt;&lt;a href="/cfs-file/__key/communityserver-wikis-components-files/00-00-00-00-32/calcoptions.jpg"&gt;&lt;img src="/resized-image/__size/940x0/__key/communityserver-wikis-components-files/00-00-00-00-32/calcoptions.jpg" alt=" " /&gt;&lt;/a&gt;&lt;/p&gt;
&lt;p&gt;&lt;/p&gt;
&lt;p&gt;You can also specify local tractive stress on a per-pipe basis:&lt;/p&gt;
&lt;p&gt;&lt;a href="/cfs-file/__key/communityserver-wikis-components-files/00-00-00-00-32/tractive_5F00_pg.jpg"&gt;&lt;img src="/resized-image/__size/940x0/__key/communityserver-wikis-components-files/00-00-00-00-32/tractive_5F00_pg.jpg" alt=" " /&gt;&lt;/a&gt;&lt;/p&gt;
&lt;p&gt;&lt;/p&gt;
&lt;p&gt;Then, after computing the model (GVF Convex Solver), you can see the calculated tractive stress and whether or not it met the target. These results are found in the properties of the conduit under the &amp;quot;Results (Tractive Stress)&amp;quot; section or in a Flextable.&lt;/p&gt;
&lt;p&gt;&lt;a href="/cfs-file/__key/communityserver-wikis-components-files/00-00-00-00-32/tractive_5F00_results.jpg"&gt;&lt;img src="/resized-image/__size/940x0/__key/communityserver-wikis-components-files/00-00-00-00-32/tractive_5F00_results.jpg" alt=" " /&gt;&lt;/a&gt;&lt;/p&gt;
&lt;p&gt;&lt;/p&gt;
&lt;p&gt;You can also color code by &amp;quot;tractive stress target exceeded&amp;quot; or &amp;quot;tractive stress target ever exceeded&amp;quot; to visualize:&lt;/p&gt;
&lt;p&gt;&lt;a href="/cfs-file/__key/communityserver-wikis-components-files/00-00-00-00-32/tractivedp.jpg"&gt;&lt;img src="/resized-image/__size/940x0/__key/communityserver-wikis-components-files/00-00-00-00-32/tractivedp.jpg" alt=" " /&gt;&lt;/a&gt;&lt;/p&gt;
&lt;p&gt;&lt;/p&gt;&lt;div style="clear:both;"&gt;&lt;/div&gt;

&lt;div style="font-size: 90%;"&gt;Tags: Tractive Force, shear stress, scour&lt;/div&gt;
</description></item><item><title>How do I set a minimum shear stress to ensure the tractive forces are large enough to scour the pipes?</title><link>https://communities.bentley.com/products/hydraulics___hydrology/w/hydraulics_and_hydrology__wiki/20512/tractive-stress-aka-tractive-force-shear-stress-calculations-and-design/revision/2</link><pubDate>Tue, 07 Apr 2015 16:47:04 GMT</pubDate><guid isPermaLink="false">6dad98f5-dbc9-4c4d-a9ba-e9da8dc6aa8e:c88a6193-17be-4d9c-b7d6-ac347ba5be13</guid><dc:creator>MPachlhofer</dc:creator><comments>https://communities.bentley.com/products/hydraulics___hydrology/w/hydraulics_and_hydrology__wiki/20512/tractive-stress-aka-tractive-force-shear-stress-calculations-and-design#comments</comments><description>Revision 2 posted to OpenFlows | Water Infrastructure Wiki by MPachlhofer on 4/7/2015 4:47:04 PM&lt;br /&gt;
&lt;h1&gt;&lt;b&gt;&lt;img width="189" height="60" style="border-width:0px;" alt=" " src="/Other/Old_Site_Files/Bentley_Folders/m/support/17560/download.aspx" /&gt;&lt;/b&gt;&lt;/h1&gt;
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&lt;td style="text-align:right;"&gt;&lt;b&gt;&amp;nbsp;&lt;/b&gt;&lt;/td&gt;
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&lt;td style="text-align:right;"&gt;&lt;b&gt;&amp;nbsp;&lt;/b&gt;&lt;/td&gt;
&lt;td style="text-align:right;"&gt;&lt;span style="font-size:medium;"&gt;&lt;b&gt;Applies To&amp;nbsp;&lt;/b&gt;&lt;/span&gt;&lt;/td&gt;
&lt;td&gt;&lt;/td&gt;
&lt;td&gt;&lt;/td&gt;
&lt;/tr&gt;
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&lt;td style="text-align:right;"&gt;&lt;strong&gt;&amp;nbsp;&lt;/strong&gt;&lt;/td&gt;
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&lt;/tr&gt;
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&lt;td style="text-align:right;"&gt;&lt;strong&gt;&amp;nbsp;&lt;/strong&gt;&lt;/td&gt;
&lt;td style="text-align:right;"&gt;&lt;strong&gt;Product(s):&lt;/strong&gt;&lt;/td&gt;
&lt;td&gt;Bentley SewerGEMS, Bentley SewerCAD&lt;/td&gt;
&lt;td&gt;&lt;/td&gt;
&lt;/tr&gt;
&lt;tr&gt;
&lt;td style="text-align:right;"&gt;&lt;strong&gt;&amp;nbsp;&lt;/strong&gt;&lt;/td&gt;
&lt;td style="text-align:right;"&gt;&lt;strong&gt;Version(s):&lt;/strong&gt;&lt;/td&gt;
&lt;td&gt;08.11.XX.XX&lt;/td&gt;
&lt;td&gt;&lt;/td&gt;
&lt;/tr&gt;
&lt;tr&gt;
&lt;td style="text-align:right;"&gt;&lt;strong&gt;&amp;nbsp;&lt;/strong&gt;&lt;/td&gt;
&lt;td style="text-align:right;"&gt;&lt;strong&gt;Environment:&amp;nbsp;&lt;/strong&gt;&lt;/td&gt;
&lt;td&gt;N/A&lt;/td&gt;
&lt;td&gt;&lt;/td&gt;
&lt;/tr&gt;
&lt;tr&gt;
&lt;td style="text-align:right;"&gt;&lt;strong&gt;&amp;nbsp;&lt;/strong&gt;&lt;/td&gt;
&lt;td style="text-align:right;"&gt;&lt;strong&gt;Area:&amp;nbsp;&lt;/strong&gt;&lt;/td&gt;
&lt;td&gt;&lt;/td&gt;
&lt;td&gt;&lt;/td&gt;
&lt;/tr&gt;
&lt;tr&gt;
&lt;td style="text-align:right;"&gt;&lt;strong&gt;&amp;nbsp;&lt;/strong&gt;&lt;/td&gt;
&lt;td style="text-align:right;"&gt;&lt;strong&gt;Original Author:&lt;/strong&gt;&lt;/td&gt;
&lt;td&gt;Mark Pachlhofer, Bentley Technical Support Group&lt;/td&gt;
&lt;td&gt;&lt;/td&gt;
&lt;/tr&gt;
&lt;tr&gt;
&lt;td style="text-align:right;"&gt;&lt;strong&gt;&amp;nbsp;&lt;/strong&gt;&lt;/td&gt;
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&lt;/tr&gt;
&lt;/tbody&gt;
&lt;/table&gt;
&lt;h1&gt;Problem&lt;/h1&gt;
&lt;p&gt;How do I set a minimum shear stress to ensure the tractive forces are large enough to scour the pipes?&lt;/p&gt;
&lt;p&gt;&lt;em&gt;Note: This only applies in SewerGEMS if you are using the GVF Convex Solver&lt;/em&gt;&lt;/p&gt;
&lt;h1&gt;Solution&lt;/h1&gt;
&lt;p&gt;You can set this in the calculation options in the location shown below&lt;/p&gt;
&lt;p&gt;&lt;a href="/cfs-file/__key/communityserver-wikis-components-files/00-00-00-00-32/TractiveForce_5F00_Sheer_5F00_Stress.png"&gt;&lt;img src="/resized-image/__size/940x0/__key/communityserver-wikis-components-files/00-00-00-00-32/TractiveForce_5F00_Sheer_5F00_Stress.png" width="412" height="986" alt=" " /&gt;&lt;/a&gt;&lt;/p&gt;
&lt;p&gt;&lt;/p&gt;&lt;div style="clear:both;"&gt;&lt;/div&gt;

&lt;div style="font-size: 90%;"&gt;Tags: shear stress, scour, tractive forces&lt;/div&gt;
</description></item><item><title>How do I set a minimum shear stress to ensure the tractive forces are large enough to scour the pipes?</title><link>https://communities.bentley.com/products/hydraulics___hydrology/w/hydraulics_and_hydrology__wiki/20512/tractive-stress-aka-tractive-force-shear-stress-calculations-and-design/revision/1</link><pubDate>Tue, 07 Apr 2015 16:46:01 GMT</pubDate><guid isPermaLink="false">6dad98f5-dbc9-4c4d-a9ba-e9da8dc6aa8e:c88a6193-17be-4d9c-b7d6-ac347ba5be13</guid><dc:creator>MPachlhofer</dc:creator><comments>https://communities.bentley.com/products/hydraulics___hydrology/w/hydraulics_and_hydrology__wiki/20512/tractive-stress-aka-tractive-force-shear-stress-calculations-and-design#comments</comments><description>Revision 1 posted to OpenFlows | Water Infrastructure Wiki by MPachlhofer on 4/7/2015 4:46:01 PM&lt;br /&gt;
&lt;h1&gt;&lt;b&gt;&lt;img width="189" height="60" style="border-width:0px;" alt=" " src="/Other/Old_Site_Files/Bentley_Folders/m/support/17560/download.aspx" /&gt;&lt;/b&gt;&lt;/h1&gt;
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&lt;td style="text-align:right;"&gt;&lt;b&gt;&amp;nbsp;&lt;/b&gt;&lt;/td&gt;
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&lt;td style="text-align:right;"&gt;&lt;span style="font-size:medium;"&gt;&lt;b&gt;Applies To&amp;nbsp;&lt;/b&gt;&lt;/span&gt;&lt;/td&gt;
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&lt;td&gt;&lt;/td&gt;
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&lt;td&gt;&lt;/td&gt;
&lt;td&gt;&lt;/td&gt;
&lt;/tr&gt;
&lt;tr&gt;
&lt;td style="text-align:right;"&gt;&lt;strong&gt;&amp;nbsp;&lt;/strong&gt;&lt;/td&gt;
&lt;td style="text-align:right;"&gt;&lt;strong&gt;Product(s):&lt;/strong&gt;&lt;/td&gt;
&lt;td&gt;Bentley SewerGEMS, Bentley SewerCAD&lt;/td&gt;
&lt;td&gt;&lt;/td&gt;
&lt;/tr&gt;
&lt;tr&gt;
&lt;td style="text-align:right;"&gt;&lt;strong&gt;&amp;nbsp;&lt;/strong&gt;&lt;/td&gt;
&lt;td style="text-align:right;"&gt;&lt;strong&gt;Version(s):&lt;/strong&gt;&lt;/td&gt;
&lt;td&gt;08.11.XX.XX&lt;/td&gt;
&lt;td&gt;&lt;/td&gt;
&lt;/tr&gt;
&lt;tr&gt;
&lt;td style="text-align:right;"&gt;&lt;strong&gt;&amp;nbsp;&lt;/strong&gt;&lt;/td&gt;
&lt;td style="text-align:right;"&gt;&lt;strong&gt;Environment:&amp;nbsp;&lt;/strong&gt;&lt;/td&gt;
&lt;td&gt;N/A&lt;/td&gt;
&lt;td&gt;&lt;/td&gt;
&lt;/tr&gt;
&lt;tr&gt;
&lt;td style="text-align:right;"&gt;&lt;strong&gt;&amp;nbsp;&lt;/strong&gt;&lt;/td&gt;
&lt;td style="text-align:right;"&gt;&lt;strong&gt;Area:&amp;nbsp;&lt;/strong&gt;&lt;/td&gt;
&lt;td&gt;&lt;/td&gt;
&lt;td&gt;&lt;/td&gt;
&lt;/tr&gt;
&lt;tr&gt;
&lt;td style="text-align:right;"&gt;&lt;strong&gt;&amp;nbsp;&lt;/strong&gt;&lt;/td&gt;
&lt;td style="text-align:right;"&gt;&lt;strong&gt;Original Author:&lt;/strong&gt;&lt;/td&gt;
&lt;td&gt;Mark Pachlhofer, Bentley Technical Support Group&lt;/td&gt;
&lt;td&gt;&lt;/td&gt;
&lt;/tr&gt;
&lt;tr&gt;
&lt;td style="text-align:right;"&gt;&lt;strong&gt;&amp;nbsp;&lt;/strong&gt;&lt;/td&gt;
&lt;td style="text-align:right;"&gt;&lt;strong&gt;&amp;nbsp;&lt;/strong&gt;&lt;/td&gt;
&lt;td&gt;&lt;/td&gt;
&lt;td&gt;&lt;/td&gt;
&lt;/tr&gt;
&lt;/tbody&gt;
&lt;/table&gt;
&lt;h1&gt;Problem&lt;/h1&gt;
&lt;p&gt;How do I set a minimum shear stress to ensure my tractive forces are large enough to scour the pipes?&lt;/p&gt;
&lt;p&gt;&lt;em&gt;Note: This only applies in SewerGEMS if you are using the GVF Convex Solver&lt;/em&gt;&lt;/p&gt;
&lt;h1&gt;Solution&lt;/h1&gt;
&lt;p&gt;You can set this in the calculation options in the location shown below&lt;/p&gt;
&lt;p&gt;&lt;a href="/cfs-file/__key/communityserver-wikis-components-files/00-00-00-00-32/TractiveForce_5F00_Sheer_5F00_Stress.png"&gt;&lt;img src="/resized-image/__size/940x0/__key/communityserver-wikis-components-files/00-00-00-00-32/TractiveForce_5F00_Sheer_5F00_Stress.png" width="412" height="986" alt=" " /&gt;&lt;/a&gt;&lt;/p&gt;
&lt;p&gt;&lt;/p&gt;&lt;div style="clear:both;"&gt;&lt;/div&gt;

&lt;div style="font-size: 90%;"&gt;Tags: shear stress, scour, tractive forces&lt;/div&gt;
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