CFD Online Discussion Forums - how to change a volScalarField in bc?

Quote:

Originally Posted by tomislav_maric (Post 342168)

From

OpenFOAM-1.6-ext/src/finiteVolume/fields/fvPatchFields/derived/parabolicVelocity

comes:

Code:

void parabolicVelocityFvPatchVectorField::updateCoeffs()

{

    if (updated())

    {

        return;

    }



    // Get range and orientation

    boundBox bb(patch().patch().localPoints(), true);



    vector ctr = 0.5*(bb.max() + bb.min());



    const vectorField& c = patch().Cf();



    // Calculate local 1-D coordinate for the parabolic profile

    scalarField coord = 2*((c - ctr) & y_)/((bb.max() - bb.min()) & y_);



    vectorField::operator=(n_*maxValue_*(1.0 - sqr(coord)));

}

This is called upcasting in C++: stripping the inherited object to the base class. All bcs are hidden *fields. No need for *_cast magic.

Just so you don't miss it , the key line is

Code:

vectorField::operator= blah blah

, this converts "this" (the class, in this case parabolicBlah...) to a vectorField.

T.

Dear Tomislav,

Thank you for your contribution, but this is missing the point slightly.
The const_cast< > here is used to be able to change an object / variable in the database, which is of type const, so theoretically not modifiable.

Kind regards,

Francois.