adding standard reference temperature T0=298.15K as default value

Author: Cristopher-Morales

Common/include/CConfig.hpp

@@ -893,6 +893,7 @@ class CConfig {
   Initial_BCThrust,                /*!< \brief Ratio of turbulent to laminar viscosity at the actuator disk. */
   Pressure_FreeStream,             /*!< \brief Total pressure of the fluid. */
   Pressure_Thermodynamic,          /*!< \brief Thermodynamic pressure of the fluid. */
+  Standard_Ref_Temperature,        /*!< \brief Standard reference temperature for multicomponent flows. */
   Temperature_FreeStream,          /*!< \brief Total temperature of the fluid.  */
   Temperature_ve_FreeStream;       /*!< \brief Total vibrational-electronic temperature of the fluid.  */
   unsigned short wallModel_MaxIter; /*!< \brief maximum number of iterations for the Newton method for the wall model */
@@ -1924,6 +1925,12 @@ class CConfig {
    */
   su2double GetPressure_Thermodynamic(void) const { return Pressure_Thermodynamic; }
 
+  /*!
+   * \brief Get the value of the standard reference temperature for multicomponent flows.
+   * \return Standard reference temperature.
+   */
+  su2double GetStandard_RefTemperature(void) const { return Standard_Ref_Temperature; }
+
   /*!
    * \brief Get the value of the non-dimensionalized thermodynamic pressure.
    * \return Non-dimensionalized thermodynamic pressure.

Common/src/CConfig.cpp

@@ -1211,6 +1211,9 @@ void CConfig::SetConfig_Options() {
   addDoubleOption("GAMMA_VALUE", Gamma, 1.4);
   /*!\brief THERMODYNAMIC_PRESSURE  \n DESCRIPTION: Thermodynamics(operating) Pressure (101325 Pa), only for incompressible flows) \ingroup Config*/
   addDoubleOption("THERMODYNAMIC_PRESSURE", Pressure_Thermodynamic, 101325.0);
+  /*!\brief STANDARD_REFERENCE_TEMPERATURE  \n DESCRIPTION: Standard reference temperature (298.15K), only for
+   * multicomponent incompressible flows) \ingroup Config*/
+  addDoubleOption("STANDARD_REFERENCE_TEMPERATURE", Standard_Ref_Temperature, 298.15);
   /*!\brief CP_VALUE  \n DESCRIPTION: Specific heat at constant pressure, Cp (1004.703 J/kg*K (air), constant density incompressible fluids only) \ingroup Config*/
   addDoubleListOption("SPECIFIC_HEAT_CP", nSpecific_Heat_Cp, Specific_Heat_Cp);
   /*!\brief THERMAL_EXPANSION_COEFF  \n DESCRIPTION: Thermal expansion coefficient (0.00347 K^-1 (air), used for Boussinesq approximation for liquids/non-ideal gases) \ingroup Config*/

SU2_CFD/include/fluid/CFluidScalar.hpp

@@ -42,6 +42,7 @@ class CFluidScalar final : public CFluidModel {
   const int n_species_mixture;            /*!< \brief Number of species in mixture. */
   su2double Gas_Constant;           /*!< \brief Specific gas constant. */
   const su2double Pressure_Thermodynamic; /*!< \brief Constant pressure thermodynamic. */
+  const su2double Ref_Temperature;        /*!< \brief Reference temperature. */
   const su2double GasConstant_Ref;        /*!< \brief Gas constant reference needed for Nondimensional problems. */
   const su2double Prandtl_Number;         /*!< \brief Prandlt number.*/
 

SU2_CFD/src/fluid/CFluidScalar.cpp

@@ -45,6 +45,7 @@ CFluidScalar::CFluidScalar(su2double value_pressure_operating, const CConfig* co
     : CFluidModel(),
       n_species_mixture(config->GetnSpecies() + 1),
       Pressure_Thermodynamic(value_pressure_operating),
+      Ref_Temperature(config->GetStandard_RefTemperature()),
       GasConstant_Ref(config->GetGas_Constant_Ref()),
       Prandtl_Number(config->GetPrandtl_Turb()),
       wilke(config->GetKind_MixingViscosityModel() == MIXINGVISCOSITYMODEL::WILKE),
@@ -213,23 +214,23 @@ su2double CFluidScalar::ComputeMeanSpecificHeatCp(const su2double* val_scalars)
 }
 
 su2double CFluidScalar::ComputeEnthalpyFromT(const su2double val_temperature, const su2double* val_scalars){
-  su2double val_Enthalpy = Cp * (val_temperature - 298.15);
+  su2double val_Enthalpy = Cp * (val_temperature - Ref_Temperature);
   return val_Enthalpy;
 }
 
 void CFluidScalar::ComputeTempFromEnthalpy(const su2double val_enthalpy, su2double* val_temperature,
                                            const su2double* val_scalars) {
   MassToMoleFractions(val_scalars);
   su2double val_cp = ComputeMeanSpecificHeatCp(val_scalars);
-  *val_temperature = val_enthalpy / val_cp + 298.15;
+  *val_temperature = val_enthalpy / val_cp + Ref_Temperature;
 }
 
 void CFluidScalar::GetEnthalpyDiffusivity(su2double* enthalpy_diffusions) {
+  const su2double enthalpy_species_N = specificHeat[n_species_mixture - 1] * (Temperature - Ref_Temperature);
   for (int iVar = 0; iVar < n_species_mixture - 1; iVar++) {
-    enthalpy_diffusions[iVar] = Density *
-                               (specificHeat[iVar] * massDiffusivity[iVar] -
-                                specificHeat[n_species_mixture - 1] * massDiffusivity[n_species_mixture - 1]) *
-                               (Temperature - 298.15);
+    const su2double enthalpy_species_i = specificHeat[iVar] * (Temperature - Ref_Temperature);
+    enthalpy_diffusions[iVar] = Density * (enthalpy_species_i * massDiffusivity[iVar] -
+                                           enthalpy_species_N * massDiffusivity[n_species_mixture - 1]);
   }
 }