void Foam::MRFZone::makeRelativeRhoFlux
(
    const RhoFieldType& rho,
    surfaceScalarField& phi
) const
{
    if (!active_)
    {
        return;
    }

    const surfaceVectorField& Cf = mesh_.Cf();
    const surfaceVectorField& Sf = mesh_.Sf();

    const vector Omega = omega_->value(mesh_.time().timeOutputValue())*axis_;

    const vectorField& Cfi = Cf;
    const vectorField& Sfi = Sf;
    scalarField& phii = phi.primitiveFieldRef();

    // Internal faces
    forAll(internalFaces_, i)
    {
        label facei = internalFaces_[i];
        phii[facei] -= rho[facei]*(Omega ^ (Cfi[facei] - origin_)) & Sfi[facei];
    }