[atul1018]

Hello CFD community

I am trying to set up a case where I know the water heights (free surface elevation) at the inlet and outlet, so the flow should be pressure-driven (water height difference). I am using interFOAM solver. I can initialize the water height using "setFields," but I am unsure how to set up the p_rgh for the inlet and outlet correctly. I have attached a picture describing my problem.

p_rgh (=p-(rho*g*h)) is the dynamic pressure, which should be based on velocity, which is not known. The total head is also not known, so specifying the dynamic head is not possible as no velocity is known at the inlet and outlet. There are some options to specify static or totalhead, which should be based on water height (e.g. prghTotalPressure, prghPressure, prghTotalHydrostaticPressure, etc.).

I tried with these options and specified as rho*g*h at the inlet and outlet. My main concern is that I have 3.2 m water height at the outlet and 2.5 m water height at the inlet (the inlet and outlet are located at different heights). This means I have 24525 Pa (rho*g*2.5) at the inlet and 31392 Pa (rho*g*3.2) at the outlet (outlet has higher static pressure than inlet). Simulations run, but results look non-physical and unrealistic. Random motion of water is observed. Please help me to set up the bc properly at the inlet and outlet, which should be based on water height.

PS: I see in the documents that when specifying p_rgh bc based on water height (prghTotalPressure, prghPressure, ...), there is an option to specify hRef. I wonder if I can use this to set up the pressure-based bc for my case.

Best Regards
Atul