Use ND Massdiffusivity. Divide by VelRef/lengthRef.

Following the laminar dynamic viscosity (for the mass Diff of course
without the densityRef)

Author: TobiKattmann

SU2_CFD/src/solvers/CEulerSolver.cpp

@@ -1030,6 +1030,9 @@ void CEulerSolver::SetNondimensionalization(CConfig *config, unsigned short iMes
   Omega_FreeStreamND = Density_FreeStreamND*Tke_FreeStreamND/(Viscosity_FreeStreamND*config->GetTurb2LamViscRatio_FreeStream());
   config->SetOmega_FreeStreamND(Omega_FreeStreamND);
 
+  const su2double MassDiffusivityND = config->GetDiffusivity_Constant() / (Velocity_Ref * Length_Ref);
+  config->SetDiffusivity_ConstantND(MassDiffusivityND);
+
   /*--- Initialize the dimensionless Fluid Model that will be used to solve the dimensionless problem ---*/
 
   /*--- Auxilary (dimensional) FluidModel no longer needed. ---*/
@@ -1289,6 +1292,12 @@ void CEulerSolver::SetNondimensionalization(CConfig *config, unsigned short iMes
         NonDimTable << "Spec. Dissipation" << config->GetOmega_FreeStream() << config->GetOmega_FreeStream()/config->GetOmega_FreeStreamND() << Unit.str() << config->GetOmega_FreeStreamND();
         Unit.str("");
       }
+      if (config->GetKind_Species_Model() != SPECIES_MODEL::NONE) {
+        if      (config->GetSystemMeasurements() == SI) Unit << "m^2/s";
+        else if (config->GetSystemMeasurements() == US) Unit << "ft^2/s";
+        NonDimTable << "Mass Diffusivity" << config->GetDiffusivity_Constant() << config->GetDiffusivity_Constant()/config->GetDiffusivity_ConstantND() << Unit.str() << config->GetDiffusivity_ConstantND();
+        Unit.str("");
+      }
     }
 
     NonDimTable.PrintFooter();

SU2_CFD/src/solvers/CIncEulerSolver.cpp

@@ -430,6 +430,10 @@ void CIncEulerSolver::SetNondimensionalization(CConfig *config, unsigned short i
   Omega_FreeStreamND = Density_FreeStreamND*Tke_FreeStreamND/(Viscosity_FreeStreamND*config->GetTurb2LamViscRatio_FreeStream());
   config->SetOmega_FreeStreamND(Omega_FreeStreamND);
 
+  const su2double MassDiffusivityND = config->GetDiffusivity_Constant() / (Velocity_Ref * Length_Ref);
+  config->SetDiffusivity_ConstantND(MassDiffusivityND);
+
+
   /*--- Delete the original (dimensional) FluidModel object. No fluid is used for inscompressible cases. ---*/
 
   delete auxFluidModel;
@@ -790,6 +794,12 @@ void CIncEulerSolver::SetNondimensionalization(CConfig *config, unsigned short i
         NonDimTable << "Spec. Dissipation" << config->GetOmega_FreeStream() << config->GetOmega_FreeStream()/config->GetOmega_FreeStreamND() << Unit.str() << config->GetOmega_FreeStreamND();
         Unit.str("");
       }
+      if (config->GetKind_Species_Model() != SPECIES_MODEL::NONE) {
+        if      (config->GetSystemMeasurements() == SI) Unit << "m^2/s";
+        else if (config->GetSystemMeasurements() == US) Unit << "ft^2/s";
+        NonDimTable << "Mass Diffusivity" << config->GetDiffusivity_Constant() << config->GetDiffusivity_Constant()/config->GetDiffusivity_ConstantND() << Unit.str() << config->GetDiffusivity_ConstantND();
+        Unit.str("");
+      }
     }
 
     NonDimTable.PrintFooter();

SU2_CFD/src/solvers/CSpeciesSolver.cpp

@@ -110,12 +110,6 @@ CSpeciesSolver::CSpeciesSolver(CGeometry* geometry, CConfig* config, unsigned sh
     }
   }
 
-  /*--- Set up fluid model for the diffusivity ---*/
-
-  su2double Diffusivity_Ref = 1.0;
-  su2double DiffusivityND = config->GetDiffusivity_Constant() / Diffusivity_Ref;
-  config->SetDiffusivity_ConstantND(DiffusivityND);
-
   /*--- Scalar variable state at the far-field. ---*/
 
   for (auto iVar = 0u; iVar < nVar; iVar++) {
@@ -127,12 +121,12 @@ CSpeciesSolver::CSpeciesSolver(CGeometry* geometry, CConfig* config, unsigned sh
   nodes = new CSpeciesVariable(Species_Inf, nPoint, nDim, nVar, config);
   SetBaseClassPointerToNodes();
 
-  /*--- Initialize the mass diffusivity ---*/
+  /*--- Initialize the mass diffusivity. Nondimensionalization done in the flow solver. ---*/
   SU2_OMP_FOR_STAT(omp_chunk_size)
   for (unsigned long iPoint = 0; iPoint < nPoint; iPoint++) {
     for (auto iVar = 0u; iVar < nVar; iVar++) {
-      const auto massDiffusivity = config->GetDiffusivity_Constant();  // TK this should be ND
-      nodes->SetDiffusivity(iPoint, massDiffusivity, iVar);
+      const auto MassDiffusivity = config->GetDiffusivity_ConstantND();
+      nodes->SetDiffusivity(iPoint, MassDiffusivity, iVar);
     }
   }
   END_SU2_OMP_FOR
@@ -309,9 +303,10 @@ void CSpeciesSolver::Preprocessing(CGeometry* geometry, CSolver** solver_contain
                                    unsigned short iMesh, unsigned short iRKStep, unsigned short RunTime_EqSystem,
                                    bool Output) {
 
+  /*--- Set the laminar mass Diffusivity for the species solver. ---*/
   SU2_OMP_FOR_STAT(omp_chunk_size)
   for (auto iPoint = 0u; iPoint < nPoint; iPoint++) {
-    const su2double mass_diffusivity = config->GetDiffusivity_Constant(); //TK:: ND
+    const su2double mass_diffusivity = config->GetDiffusivity_ConstantND();
 
     for (auto iVar = 0u; iVar < nVar; iVar++) {
       nodes->SetDiffusivity(iPoint, mass_diffusivity, iVar);