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model a tank in rising main in WaterGEMS

Dear Jesse,

Thanks for your earlier reply. it really helped me. but now i am facing another problem. when i am modelling a ground storage tank in rising main, it effects the hydraulic grade line of all previous nodes. how can i avoid this.

and if i change the elevations to higher elevations (which are not the actual ones) its make impact and negative pressure changes to positive pressure. how can i avoid the effect on previous node because i have free falling water to ground storage tank.

Suhail Latif

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  • Hello Suhail,

    Could you please attach a screenshot of your model setup, it will give us clarity of the query.
    Or if possible, please upload your model files and specify about the area in question.

    There are two options for sharing your model on Communities, whichever you choose please be sure to zip your files first. The first option is to attach the zip file containing your model to your reply on the forum using the Advanced Reply Editor (you'll find the link below and to the right of the reply box). If your data is confidential please use the instructions in the link below to send it via Bentley Sharefile. Files uploaded to Sharefile can only be viewed by Bentley employees. Please be sure to reply on this thread with the name of the file after it has been uploaded.

    communities.bentley.com/.../7079.communities-secure-file-upload
    If you upload the files to Sharefile, please post here with the name of the files so that we know they are available.

    Regards,

    Sushma Choure

    Bentley Technical Suppport

  • 4382.1780.Model.rar

    Reply from Suhail , posted by mistake in a new post -

    Hello Ms Sushma,

    i am attaching the model for your review. actually tanks affecting the hydraulic grade line of previous nodes, if i removed the tank the i got very smooth line. tank is under ground tank and inlet is on top. so it should not affect the previous nodes .

    Suhail Latif

    Regards,

    Sushma Choure

    Bentley Technical Suppport

  • Hello Suhail,

    When you add tank in the system, the total hydraulics changes as its a boundary element. So the model looks at the tank to get the HGL's in the model.

    You can do a trick by putting an air valve just upstream of the tank.

    Or you could model it in SewerGEMS, which will not affect the upstream hydraulics unless the water level is higher than the incoming pipe.

    Regards,

    Sushma Choure

    Bentley Technical Suppport

  • Thanks Ms Sushma,
    i tried it by adding air valve u/s of the tanks but they have no effect on HGL. now, i model it in indirect way by dividing the network just before the under ground tanks and now HGL is really goood but my Project rising main is splitted in three parts.
    so, i think we cannot run directly our model in WaterGEMS with under ground tanks as under ground tanks will affect the HGL on previous nodes.

    Suhail Latif
  • For the Air Valve to have an effect on the HGL during a calculation, you need to set the 'Treat Air Valve as Junction?' attribute to False. Otherwise, the solver just assumes that this element behaves like a regular Junction element during a calculation.

    Regards,

    Mal

          

    Answer Verified By: Sushma Choure 

  • As Sushma pointed out, a tank is a boundary condition in WaterCAD and WaterGEMS, essentially specifying a known hydraulic grade from which the solves other hydraulic grades.

    If your tank fills from the top, and the boundary HGL of the water water surface effects only the downstream side, then you could use the top-filling tank feature in place of the air valve node. You can read more about it here:

    Modeling top fill tanks and throttling inlet valves

    However, I noticed that the maximum elevation in your tank (408 ft) is less than the elevation of the upstream node (J-14, at 410 ft).

    If you use the air valve approach, you can read more about its use in a steady state/EPS here:

    Modeling Air Valves At High Points in WaterCAD or WaterGEMS


    Regards,

    Jesse Dringoli
    Technical Support Manager, OpenFlows
    Bentley Communities Site Administrator
    Bentley Systems, Inc.

    Answer Verified By: Sushma Choure 

Reply
  • As Sushma pointed out, a tank is a boundary condition in WaterCAD and WaterGEMS, essentially specifying a known hydraulic grade from which the solves other hydraulic grades.

    If your tank fills from the top, and the boundary HGL of the water water surface effects only the downstream side, then you could use the top-filling tank feature in place of the air valve node. You can read more about it here:

    Modeling top fill tanks and throttling inlet valves

    However, I noticed that the maximum elevation in your tank (408 ft) is less than the elevation of the upstream node (J-14, at 410 ft).

    If you use the air valve approach, you can read more about its use in a steady state/EPS here:

    Modeling Air Valves At High Points in WaterCAD or WaterGEMS


    Regards,

    Jesse Dringoli
    Technical Support Manager, OpenFlows
    Bentley Communities Site Administrator
    Bentley Systems, Inc.

    Answer Verified By: Sushma Choure 

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