[elb31]

Hello everybody

I am a newbie in OpenFOAM trying to develop a boundary condition derived from fixedValue. I would like to impose a value for a field, let's say D, such as each face of the boundary patch assumes the value:

D[faceI] = D.oldTime()[faceI] + DD[faceI]

Where DD is the field representing the increment of D over the past time-step.

Have you got any suggestions on how I can approach this simple problem?

Thank you for any help/suggestion !
- elb

Edit:

To be more precise in my request, what I've tried to do is modifying the updateCoeffs() function from one of the existing derived BC from fixedValue in the following way:

void calculateTotalField::updateCoeffs()
{
    if (this->updated())
    {
        return;
    }   

    const volVectorField& Dold =
            db().lookupObject<volVectorField>("D").oldTime();

    const volVectorField& DD =
            db().lookupObject<volVectorField>("DD");
    
    vectorField disp;
    disp = Dold.boundaryField()[patch().index()] + DD.boundaryField()[patch().index()];

    fvPatchField<vector>::operator==(disp);

    fixedValueFvPatchVectorField::updateCoeffs();
}

Is this a valid solution?

Thanks!
-elb