Code Question

[HyungseonSong-plasma]

In CHeatSolver.cpp, I have a question about BC_onjugateHeat_Interface.

    if ((config->GetKind_CHT_Coupling() == CHT_COUPLING::DIRECT_TEMPERATURE_ROBIN_HEATFLUX) ||
        (config->GetKind_CHT_Coupling() == CHT_COUPLING::AVERAGED_TEMPERATURE_ROBIN_HEATFLUX)) {

      const su2double Tinterface = nodes->GetTemperature(iPoint);
      const su2double Tnormal_Conjugate = GetConjugateHeatVariable(val_marker, iVertex, 3) / Temperature_Ref;

      const su2double HeatFluxDensity = thermal_diffusivity * (Tinterface - Tnormal_Conjugate);
      HeatFlux = HeatFluxDensity * Area;

      if (implicit) {
        su2double Jacobian_i[] = {-thermal_diffusivity*Area};
        Jacobian.SubtractBlock2Diag(iPoint, &Jacobian_i);
      }
    }
    else {
      const su2double HeatFluxDensity =
          GetConjugateHeatVariable(val_marker, iVertex, 1) / config->GetHeat_Flux_Ref();
      HeatFlux = HeatFluxDensity*Area;
    }

I wonder why there are no Jacobian setting in else {}.

      if (implicit) {
        su2double Jacobian_i[] = {-thermal_diffusivity*Area};
        Jacobian.SubtractBlock2Diag(iPoint, &Jacobian_i);
      }

this code should move out if {} else {} in my thought or Is it intended to just use explicit If user does not use ROBIN ?

[pcarruscag]

Because in that case the heat flux is not a function of a solution variable of the solver.
In the if {} part heat flux depend on const su2double Tinterface = nodes->GetTemperature(iPoint); whereas in the else {} it is just a value that comes from another solver.