CFD Online Discussion Forums - fixedGradient Boundary Condition

Dear Foamers,

I am currently developing a boundary condition to interpolate values over time and space like the timeVaryingMappedFixedValue patch, but for traction/pressure (tractionDisplacement patch) which inherits the fixedGradient patch.

After the interpolation weight (s) is calculated, the timeVaryingMappedFixedValue patch assigns values through this command

Code:

00710 this->operator==((1-s)*startSampledValues_ + s*endSampledValues_);

From this post, I understood that the "==" operator imposes assigned values on the patch (if a "=" is used then new values will not be imposed).

On the other hand, the tractionDisplacement BC assigns its values to gadient() as:

Code:

gradient() =

    (

        (traction_ + pressure_*n)/rho.value()

      + twoMuLambda*fvPatchField<vector>::snGrad() - (n & sigmaD)

    )/twoMuLambda;

My question is: Is it OK to just assign calculated values "gradient" to the gradient() using a "=" operator for each time step? Or is some forcing of the values needed?

Best regards,
Hisham