Hi all, I have this situation.
A tank is filling from the top and I want to simulate the hammer effect on the line. I see the HGL from the initial condition at the invert of the pipe which is correct, but when I run the transient the pressure falls to the initial level setting of the tank, thus reflecting a wave that is not supposed to be there. It seems to me that it is taking as initial HGL the initial level of the tank instead of the invert level from the top filling pipe.
Am I setting something wrongly here?
The pump is set to trip at 5 seconds delay.
Best regards and thank you in advance.
Hello Denis,
For a transient simulation, a top-filling tank should be modeled as a discharge to atmosphere element. This way, HAMMER correctly sees it as a free-discharge (spilling into the top of the tank). Otherwise it will "see" it as being connected to a boundary hydraulic grade (water surface), which would not be appropriate since a transient pressure wave would not be able to traverse the air gap where the water spills into the tank.
See the section called "Top-Fill Tanks in a Transient Simulation in HAMMER" in the following article from our Wiki: Modeling top fill tanks and throttling inlet valves
Regards,
Jesse DringoliTechnical Support Manager, OpenFlowsBentley Communities Site AdministratorBentley Systems, Inc.
Answer Verified By: Larry Abla
Thank you Jesse. It is running ok now that I used the discharge to atmosphere.