[Hawxliquid]

Hi everyone!


I am trying to do a simulation of a river and its surrounding. I made an example mesh and you can find the files here : https://www.dropbox.com/scl/fi/nu1k4...=s52n6k84&dl=0


I am using interFoam, but can not get any results. I have several issue, but the main one for now is the weird behaviour of the air part, as seen in the image. There seems to be some kind of weird unstability arising.
Do you have any idea of the BCs I should be using in that case?
Here are the main current ones (to reference to the image, if you do not want to download the example case)


alpha.water (before the setField do define a bit of water at the inlet)

    inlet
    {
        type            variableHeightFlowRate;
        lowerBound      0;
        upperBound      1;
        value           uniform 0;
    }

    walls
    {
        type            zeroGradient;
    }

    outlet
    {
        type            zeroGradient;
        value           uniform 0;
    }

    atmosphere
    {
        type            inletOutlet;
        inletValue      uniform 0;
        value           uniform 0;
    }

    side_atmosphere
    {
        type            zeroGradient;
        value           uniform 0;
    }

U

    inlet
    {
        type            variableHeightFlowRateInletVelocity;
        flowRate        1;
        alpha           alpha.water;
        value           uniform (0 0 0);
    }

    walls
    {
        type            noSlip;
    }

    atmosphere
    {
        type            pressureInletOutletVelocity;
        value           uniform (0 0 0);
    }
    side_atmosphere
    {
        type            zeroGradient;

    }
    outlet
    {
        type            zeroGradient;
    }

p_rgh

    atmosphere
    {
        type            totalPressure;
        p0              uniform 0;

    }


    inlet
    {
        type            zeroGradient;

    }

    walls
    {
        type            fixedFluxPressure;
    }


    side_atmosphere
    {
        type            zeroGradient;
    }
    outlet
    {
        type            zeroGradient;
    }

Thanks!


Screenshot 2025-11-19 110927.jpg
Screenshot 2025-11-19 111817.jpg
Screenshot 2025-11-19 111830.jpg