How do I determine the residual head at the inlet of the Overhead Water Tank which is filling from the top in WaterGEMS?
If you are using the top-filling tank feature in WaterGEMS and you have "inlet valve throttles" set to "true", then the tank will only fill if the hydraulic grade is above the inlet pipe invert ("level (inlet invert)" plus the "elevation (base)") plus the headlosses through the inlet valve.
So, if the "residual head" you're looking for is the hydraulic grade on the upstream side of the tank's inlet pipe, you would look at the result field called "Hydraulic grade (Inlet Valve, from)". This is located in the "Results (separate inlet)" section of the tank properties and graph series options.
Alternatively, you could simply look at the hydraulic grade at an upstream junction (if you can neglect headloss between that junction at the tank inlet).
If you are not using the "inlet valve throttles" feature, then the upstream HGL will be equal to the invert elevation of the tank inlet pipe (meaning, a pressure of zero measured at the tank inlet elevation).
You can see an illustration and example model in this article from our Wiki: Modeling top fill tanks and throttling inlet valves
If this isn't what you are looking for, then as Yashodhan mentioned, please provide a bit more details on what you are looking for here and what you are trying to accomplish.
Regards,
Jesse DringoliTechnical Support Manager, OpenFlowsBentley Communities Site AdministratorBentley Systems, Inc.
Answer Verified By: Sushma Choure