FLOW CONTROL RESERVOIR TO TANK

Question

Hello Bentley, 
 Why is it hard to control flow in an open system? I am getting undesired flow from the reservoir to the tank however how much I specify the demand at different nodes. I don't want to use a flow control valve since it adds excessive/abnormal head to my model not a similar case in the real life scenario since the position of the flow control valve is right at the intake structure /weir. My worry is that I Fear it might have less to near NO effects unlike it has been exaggerated. 
 see the attached .how can I cure this?

ALLAN MULONGO · Answer

positioning the FCV at the end of the pipeline cured my problem guys. Thanks for your support family

Craig Calvin · Answer

Hello Mulongo, 
 How much flow do you expect to be going into the tank? 
 I recommend modeling the actual system as accurately as you can. If there are demands and a flow control valve then include them in the model. 
 When I opened the model there weren't any demands applied. After computing, there was 28 l/s going into the tank. The lowest pressure was about -28.6 mH2O. 
 After applying a demand of 0.2 l/s at each junction (about 20 l/s total) there was 17 l/s flowing into the tank. However, the lowest pressure was about -40 mH20. 
 Then I added a flow control valve next to the tank and limited the flow to 10 l/s. The lowest pressure was about -20 and the highest pressure was about -20.

Craig Calvin · Answer

Flow can move by gravity based on boundary condition HGL differences. When you don't apply any demands the headloss is what restricts the flow. Using an FCV would be another way to restrict flow, but you can't use one. 
 Another option would be to reduce the pipes' diameters or increase the roughness.

FLOW CONTROL RESERVOIR TO TANK

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