CFD Online Discussion Forums - "=" or "==" when I modify BC (fixedGradient) during run ?

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"=" or "==" when I modify BC (fixedGradient) during run ?

Hi!

I wonder what is the correct code form to modify the BC during runs.

I know that for a fixedValue BC the "==" sign is required to overwrite the orginal BC. For example:

Code:

phiS.boundaryField()[patchID]== phib.boundaryField()[patchID];

Now, if I want to modify a fixedGradient, it seems to me that "==" doesn't overwrite the orginal BC but "=" does. My piece of code is the following:

Code:

    fixedGradientFvPatchScalarField& gradpPatch=refCast<fixedGradientFvPatchScalarField>(p.boundaryField()[patchID]); 

    scalarField& gradpField =  gradpPatch.gradient();

    gradpField = fluxP;

Do you have an explanation ?

Best regards,
Cyp