[TheMadHungarian]

Hello,

New OF user here, I have been using OpenFOAM for about a year now and constantly learning new things.

I have a simulation which is using 3 materials (air, L1, L2) and I use the interMixingFoam solver. While everything is assumed to be under the same pressure the results look great. But as soon as I introduce a high pressure range for one of the materials the solver does not solve it - while things look great at 0 at the next time step the pressure reduces to below atmospheric which is not possible.

The simulation is the following: there is a large tall vertical tank with the tank closed on the top end and open on the bottom. The tank is split in about half inside with a wall but the wall has an opening on it - so the liquid in the top half of the tank can flow down onto the liquid in the bottom half. Since there is an opening on the bottom of the tank the mixture of the two liquids will begin to flow out of the tank as well.
Problem: everything goes well as long as the top L1 is under atmospheric (ambient) pressure. But when I try to increase the pressure above the liquid in the top of the tank the solution shows that the pressure reduced yet the L1 and L2 did not begin to mix or even flow yet.
I think there is something wrong the way I define the IC and/or BC for the problem.

I think the initial conditions are set up correctly as paraFoam shows a large pressure are above the top liquid in the tank - so far so good. But at 0.005 seconds it shows that the high pressure area is gone, which is not possible - the high pressure is used to "drive" the top liquid (L2) out of the tank towards the bottom (L1) liquid.

Edit: a good example of what I am trying to do is the DamBreak tutorial in the interMixingFoam section.
But I would change setFields from this:

regions
(
    boxToCell
    {
        box (0 0 -1) (0.1461 0.292 1);
        fieldValues
        (
            volScalarFieldValue alpha.water 1
        );
    }
);

to this:

regions
(
    boxToCell
    {
        box (0 0 -1) (0.1461 0.292 1);
        fieldValues
        (
            volScalarFieldValue alpha.water 1
        );

        box (0 0 -1) (0 0.5 1);
        fieldValues
        (
            volScalarFieldValue p_rgh 1e5
        );
    }
);

I have the simulation files attached.

Any helpful input comment etc is welcome, I am at my wits' end !

Thanks,

Andy