[FUDM]

Hi!

I'm trying to simulate a room (4 walls) at a specific air pressure. I thought of defining the "specified pressure" boundary condition at each surface, indicating the pressure value. However, my question is what would be the pressure in the room's void space (within the boundaries)?

Thanks for the help!

[JBurnham]

The pressure boundary condition is set at the center of the first boundary condition "ghost" cell which is outside of the domain. You can find the center of this cell in Diagnostics > Preprocessor Summary > Search for "mesh generated in z", and look at the zk values for n = 2 and nmax - 1.

Once you know the locations Zmax and Zmin of the boundary pressures on z-max and z-min boundaries, set the pressures Pzmax and Pzmin = Pzmax + RHO*h*g, where h = Zmax - Zmin.

Then set the initial conditions > global > initial pressure > hydrostatic. Now you will have a hydrostatic pressure distribution in the domain that will be maintained throughout the simulation unless the fluid flow disturbs it.

If you make a mistake you will see big velocity drafts of many meters per second going out this sides or bottom of the domain.

[FUDM]

Thank you very much for the help! I'll see what I can do!