[enthusiast]

I am conducting two-phase flow simulations in a separator with 3 inlets and 2 outlets using twoPhaseEulerFoam in OF version 8.

The inlet velocity BC is specified at 2 inlets and pressure outlet BC is specified at the 2 outlets.

Initially, half of the separator volume is filled with water using setFieldDict.

I am expecting the water level to remain constant but strangely the water level increases.

I was expecting flow in = flow out, the velocity vector at the water outlet is not correctly calculating the water velocity at the outlet.

I have attached my BC for U, p_rgh, alpha fields below.

FoamFile
{
    version     2.0;
    format      ascii;
    class       volScalarField;
    location    "0";
    object      alpha.water;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

dimensions      [0 0 0 0 0 0 0];

internalField   uniform 0;

boundaryField
{	
	inlet1
    {
        type            fixedValue;
        value           uniform 0.698;
    }
	
	inlet2
    {
        type            fixedValue;
        value           uniform 0.698;
    }
	
	inlet3
    {
        type            fixedValue;
        value           uniform 0.698;
    }
	
	walls
    {
        type            zeroGradient;
    }

	baffle1
    {
        type            zeroGradient;
    }
	
	baffle2
    {
        type            zeroGradient;
    }
	
	baffle3
    {
        type            zeroGradient;
    }
	
    outlet1
    {
        type            inletOutlet;
        phi             phi.water;
        inletValue      uniform 1;
        value           uniform 1;
    }
	
	outlet2
    {
        type            inletOutlet;
        phi             phi.water;
        inletValue      uniform 0;
        value           uniform 0;
    }

}


// ************************************************************************* //

FoamFile
{
    version     2.0;
    format      ascii;
    class       volScalarField;
    location    "0";
    object      alpha.oxygen;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

dimensions      [0 0 0 0 0 0 0];

internalField   uniform 1;

boundaryField
{	
	inlet1
    {
        type            fixedValue;
        value           uniform 0.302;
    }
	
	inlet2
    {
        type            fixedValue;
        value           uniform 0.302;
    }
	
	inlet3
    {
        type            fixedValue;
        value           uniform 0.302;
    }
	
	walls
    {
        type            zeroGradient;
    }
		
	baffle1
    {
        type            zeroGradient;
    }
	
	baffle2
    {
        type            zeroGradient;
    }
	
	baffle3
    {
        type            zeroGradient;
    }
	
    outlet1
    {
        type            inletOutlet;
        phi             phi.oxygen;
        inletValue      uniform 0;
        value           uniform 0;
    }
	
	outlet2
    {
        type            inletOutlet;
        phi             phi.oxygen;
        inletValue      uniform 1;
        value           uniform 1;
    }

}


// ************************************************************************* //

FoamFile
{
    version     2.0;
    format      ascii;
    class       volScalarField;
    object      p_rgh;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

dimensions          [1 -1 -2 0 0 0 0];

internalField       uniform 4.01325e5;

boundaryField
{
    inlet1
    {
        type               fixedFluxPressure;
        value              $internalField;
    }
	
	inlet2
    {
        type               fixedFluxPressure;
        value              $internalField;
    }
	
	inlet3
    {
        type               fixedFluxPressure;
        value              $internalField;
    }
	
	walls
    {
        type               fixedFluxPressure;
        value              $internalField;
    }

	baffle1
    {
        type               fixedFluxPressure;
        value              $internalField;
    }
	
	baffle2
    {
        type               fixedFluxPressure;
        value              $internalField;
    }
	
	baffle3
    {
        type               fixedFluxPressure;
        value              $internalField;
    }
	
    outlet1 //water outlet
    {
        type               prghPressure;
        p                  $internalField;
        value              $internalField;
    }
	
    outlet2 //oxygen outlet
    {
        type            fixedValue;
        value           $internalField;
    }
}

// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

FoamFile
{
    version     2.0;
    format      binary;
    class       volVectorField;
    object      U.water;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

dimensions      [0 1 -1 0 0 0 0];

internalField   uniform (0 0 0);

boundaryField
{
    inlet1
    {
        type            fixedValue;
        value           uniform (0 0 3.83);
    }
	
	inlet2
    {
        type            fixedValue;
        value           uniform (0 0 -3.83);
    }
	
	inlet3
    {
        type            fixedValue;
        value           uniform (0 0 -3.83);
    }
	
	walls
    {
        type               noSlip;
        
    }

	baffle1
    {
        type               noSlip;
        
    }
	
	baffle2
    {
        type               noSlip;
        
    }
	
	baffle3
    {
        type               noSlip;
        
    }
	
    outlet1
    {
        type               pressureInletOutletVelocity;
        phi                phi.water;
        value              $internalField;
    }
	
    outlet2
    {
        type               pressureInletOutletVelocity;
        phi                phi.water;
        value              $internalField;
    }
}

// ************************************************************************* //

FoamFile
{
    version     2.0;
    format      binary;
    class       volVectorField;
    object      U.oxygen;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

dimensions      [0 1 -1 0 0 0 0];

internalField   uniform (0 0 0);

boundaryField
{
    inlet1
    {
        type            fixedValue;
        value           uniform (0 0 1.66);
    }
	
	inlet2
    {
        type            fixedValue;
        value           uniform (0 0 -1.66);
    }
	
	inlet3
    {
        type            fixedValue;
        value           uniform (0 0 -1.66);
    }
	

    walls
    {
        type               fixedValue;
        value              uniform (0 0 0);
    }

	baffle1
    {
        type               fixedValue;
        value              uniform (0 0 0);
    }
	
	baffle2
    {
        type               fixedValue;
        value              uniform (0 0 0);
    }
	
	baffle3
    {
        type               fixedValue;
        value              uniform (0 0 0);
    }
	
    outlet1
    {
        type               pressureInletOutletVelocity;
        phi                phi.oxygen;
        value              $internalField;
    }
	
    outlet2
    {
        type               pressureInletOutletVelocity;
        phi                phi.oxygen;
        value              $internalField;
    }
}

// ************************************************************************* //

I have also attached the water level at 0 sec and 20 sec simulation time.

out.0000.png

out.0399.png

Thank you.