CFD Online Discussion Forums - Outlet pressure boundary condition in interFoam

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- - Outlet pressure boundary condition in interFoam (https://www.cfd-online.com/Forums/openfoam-solving/120350-outlet-pressure-boundary-condition-interfoam.html)

liquid rebounds at the outlet

Quote:

Originally Posted by arnau1985 (Post 463568)

Hi Thibault,

I solved the problem to a certain extent. What I did is the following: I realized that supercritical flow outlets in OpenFOAM behave as expected as long as there is no flow separation (I got the idea from this tutorial). So I replaced the spill of my model with a descending slope (see attached picture), set all the variables at the outlet to zeroGradient (except for pressure, which I set to buoyantPressure) and everything ran smoothly.

I am still trying to do all this in a more elegant way without spills, slopes and so on: just directly imposing a given water depth and a hydrostatic pressure profile at the outlet. I will try to keep you informed of my findings.

Good luck!

Arnau.

Dear Arnau,
I have the same problem but for a liquid jet and the jet does not go out, I tried many different combination of BC. Have you found an elegant way to solve the problem? does using buoyantPressure for P_egh at the outlet is enogh?
Best wishes,
Sandy,

pressure boundary conditions

Quote:

Originally Posted by Artur (Post 438846)

Ok, I see what you mean now. Unfortunately I don't know much about gravity driven flow simulations as I use interFoam only to calculate the free surface of moving ships so hopefully someone more experienced will have a look at your post. In the meantime, your mesh seems fairly coarse in the outlet region, have you tried refining it a bit to see if it makes a difference?

P.S. I don't think that the horizontal orientation of the outlet should make any difference because it seems like it should be (by enlarge) perpendicular to the flow of the jet.

Hi, i'm dealing with a trank drainage problem. I'm using the solver interfoam, and i don't know how to set the boundary conditions in the outlet for p_rgh. Any suggestions?

Quote:

Originally Posted by arnau1985 (Post 439104)

Yes, since I thought the horizontal outlet may have been the cause of my troubles, I tried to define as outlet only the vertical patches (again, I tried both cases, but the one I uploaded was the last one). Anyway, the result is the same: the water keeps on blocking at the outlet.

Thanks for your time, Pablo! :)

Hi! have you been able to resolve this issue?

I am having a simular issue wherein my two phase liquidliquid flow at a pipe outlet starts getting blocked becuase of this pressure/alpha boundary condition issue with interfoam. There is flo reversal across the outlet so i can t use fixed values.

thanks!