CFD Online Discussion Forums - New BC: problems with asking velocity vector

Dear foamers

I am making a new boundary condition that depends on the direction of the velocity vector U (if you is going in the positive Y direction, the inlet velocity should be U1 and if it it is going in the negative Y direction, velocity should be U2).
It compiles but gives wrong results ( I think it is because the asked U value is not the velocity vector of the cell just above the boundary?)

Code:

void Foam::myInletOutletWithNormalVel::updateCoeffs() // 

{

    if (updated())

    {

        return;

    }



    const fvPatchVectorField& Up =

        patch().lookupPatchField<volVectorField, vector>(UName_);     //searches value of U

 

    scalarField normal = Up.component(1);       

    scalarField valueFraction =(1-pos((normal)));           



   vectorField::operator=(valueFraction*U1_ + (1.0 - valueFraction)*U2_); //

 

    fixedValueFvPatchVectorField::updateCoeffs();



}

Could someone with some more C++ experience help me out and say what I am doing wrong :)?

Thank you!!!