OpenFOAM

For P
dimensions      [0 2 -2 0 0 0 0];

internalField   uniform 0;

boundaryField
{
    inlet
    {
        type            totalPressure;
        rho             rho;
        psi             none;
        gamma           1;
        p0              uniform 50;
        value           uniform 50;
    }
    outlet
    {
        type            fixedValue;
        value           uniform 0;
    }
    walls
    {
        type            zeroGradient;
        gradient        uniform 0;
        value           uniform 0;
    }