EPS

Question

If I do an EPS and then decide to annotate the pipes and junctions with respective pressures and nodes, is there a way to identify which time step of the EPS is being displayed? I have a hard time understanding the results on the model itself. My summary is all green and everything is balanced per the results but if I try to get the system annotate everything the numbers are not what I expected. The same question applies for the Flex tables. I'm having trouble understanding what time step is showing up in the flex tables. I'm new to watergems and just need some help interpreting the results.

Jesse Dringoli · Answer

Thanks for the extra screenshots. I assume the top-left shows the demand collection for the junction in question. 
 Please check the "Daily Factors" and "Monthly Factors" tabs in the demand pattern to make sure they are not set to 0.1 (the calculated demands you're showing appear to be one tenth of what they should be based on the hourly pattern multipliers). 
 If this does not help, can you simplify the model down to one pipe for example (reservoir > pipe > junction in question) and remove any other library components, and send a copy of that using the private method mentioned in this article ? 
 If that is not possible, please send me a private message with your company information ("Site ID" found under File > Help > About) so that I can open a Service Request for this and try to schedule a meeting if your company has a SELECT or ELS subscription. I was not able to locate your company based on your Communities account email address.

Jesse Dringoli · Answer

Great. I have added this to the related article: Calculated demand does not match entered demand

Larry Abla · Answer

Yusuf Rashid, 
 First, make sure the Auto Refresh option is selected (has a checkmark beside it) in View - Refresh. This Wiki article contains more information. 
 The results are probably reflecting the first timestep before water begins to flow through the system. See this Wiki article for instructions on how to look at certain time steps. 
 Also, as a new user, you might find the following article to be a good resource - Learning Resource Guide for new users of Bentley WaterGEMS and WaterCAD . 
 Please let us know if you need more information or if you have trouble with any of the links provided. 
 Thank-you, Larry

Jesse Dringoli · Answer

Hi Yusuf, 
 It is best to start a new thread for a new question. 
 It would be best to see a copy of the model plus steps to reproduce, or a more detailed description. 
 Without that I can only guess that you might be encountering pattern smoothing - generally speaking the calculated demand at a node during EPS will be equal to the base flow multiplied by the pattern multiplier at the given timestep, but depending on the type of pattern, some averaging is done such that the calculated flow will be slightly different than a basic hand calculation. See more here: Demand calculation with Continuous vs Stepwise patterns 
 If you need to provide a copy of the model for review, see: Sharing Hydraulic Model Files on the OpenFlows Forum

Jesse Dringoli · Answer

Can we focus in on one junction? For example the first one in the list in the screenshot in your previous reply with a base demand of 14 gpm. With the pattern assigned to it, the peak multiplier at around 15 hours is about 1.8, so you'd expect to see roughly 25 gpm as the calculated demand at that junction at hour 15. When you move the Time Browser to hour 15 and look at the properties of that junction, what do you see in the "Demand (Calculated)" result field? 
 Do you have any active demand adjustments applied in the calculation option set assigned to this scenario? See this article: Calculated demand does not match entered demand

Jesse Dringoli · Answer

Ok. Did you check the active demand adjustment calculation option? If that is set to multiple or divide all demands for example, it would further adjust the calculated demand and could explain why the calculated demand is much lower than what you expect. See the article I mentioned in my previous reply.

Jesse Dringoli · Answer

The graph in your previous reply seems to be the flow in a pipe, not the calculated demand. Where is this pipe in relation to the demand? (is the demand at a dead-end, and this is the pipe upstream of it?) 
 Can you graph the calculated demand at that node in question, or move the Time Browser to hour 15 and provide a screenshot of the Results section of the properties where the calculated demand is shown? 
 Are you certain that you're looking at the correct pattern assigned to that node, that you you're computing the correct scenario and that you're looking at the calculation options assigned to that scenario? 
 Do you have pressure dependent demands applied? 
 Beyond this, it would be more efficient to obtain a copy of the model , or perhaps a cut-down/simplified version that demonstrates the problem.

Jesse Dringoli · Answer

Thanks - some follow-up questions for you: 
 1) The calculation options screenshot does not include the Pressure Dependent demand option near the bottom - can you confirm that PDD is not enabled? (this would adjust demands based on pressure). 
 2) The screenshots seem to be showing the scenario named "Base" (note the red check mark next to "base". Are you sure that this is the scenario you are computing when observing the results in question? 
 3) Do either of those two other calculation option sets have a demand adjustment applied? (in case maybe they are assigned to the scenario you're looking at) 
 4) Even though the "Demand Adjustment" calculation option indicates "None", does it have any effect if you switch this to use a global multiplier of 1.0? (then re-compute the model) 
 5) What version of WaterGEMS are you using? You can find this under File > Help > About. The latest is 10.03.01.08. Although it is unlikely that this would matter, if you are using an older version, it may be best to try upgrading . 
 Again, it would be much easier for us to determine the cause of this problem if we could see the model, or a simplified version that demonstrates the problem.

EPS

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