Fixed CL: write the finite difference dCX/dCL to flow.meta regardless of the screen output frequency

SU2_CFD/include/output/CFlowOutput.hpp

@@ -364,6 +364,32 @@
    */
   void SetFixedCLScreenOutput(const CConfig *config);
 
+  /*!
+   * \brief Check if the fixed CL driver changed the AoA at the current iteration
+   *        (in finite difference mode this is the start of the finite difference step).
+   * \return <TRUE> if the AoA was changed.
+   */
+  bool FixedCLStartFD() const {
+    return fabs(GetHistoryFieldValue("CL_DRIVER_COMMAND")) > EPS;
+  }
+
+  /*!
+   * \brief Check if the AoA was restored at the current iteration
+   *        (in finite difference mode this is the end of the finite difference step).
+   * \return <TRUE> if the AoA is equal to the previous AoA.
+   */
+  bool FixedCLEndFD() const {
+    return GetHistoryFieldValue("AOA") == GetHistoryFieldValue("PREV_AOA");
+  }
+
+  /*!
+   * \brief Store the iteration at which the finite difference step of the fixed CL driver starts and
+   *        write the meta data file with the finite difference derivatives at its end.
+   * \note Called every iteration, independently of the screen output frequency.
+   * \param[in] config - Definition of the particular problem per zone.
+   */
+  void SetFixedCLFiniteDifference(const CConfig *config);
+
   /*!
    * \brief Compute the ratio of the stochastic energy backscatter to the turbulent energy dissipation.
    * \param iPoint - Index of the point.

SU2_CFD/src/output/CFlowCompOutput.cpp

@@ -470,6 +470,10 @@ void CFlowCompOutput::LoadHistoryData(CConfig *config, CGeometry *geometry, CSol
 
   SetAerodynamicCoefficients(config, flow_solver);
 
+  /*--- Fixed CL finite difference step, uses the AOA set above. ---*/
+
+  if (config->GetFixed_CL_Mode()) SetFixedCLFiniteDifference(config);
+
   if (config->GetViscous()) {
     SetHistoryOutputValue("BUFFET", flow_solver->GetTotal_Buffet_Metric());
   }

SU2_CFD/src/output/CFlowOutput.cpp

@@ -4245,7 +4245,7 @@ void CFlowOutput::LoadTimeAveragedData(unsigned long iPoint, const CVariable *No
 void CFlowOutput::SetFixedCLScreenOutput(const CConfig *config){
   PrintingToolbox::CTablePrinter FixedCLSummary(&cout);
 
-  if (fabs(historyOutput_Map["CL_DRIVER_COMMAND"].value) > 1e-16){
+  if (FixedCLStartFD()){
     FixedCLSummary.AddColumn("Fixed CL Mode", 40);
     FixedCLSummary.AddColumn("Value", 30);
     FixedCLSummary.SetAlign(PrintingToolbox::CTablePrinter::LEFT);
@@ -4255,15 +4255,14 @@ void CFlowOutput::SetFixedCLScreenOutput(const CConfig *config){
     FixedCLSummary << "Previous AOA" << historyOutput_Map["PREV_AOA"].value;
     if (config->GetFinite_Difference_Mode()){
       FixedCLSummary << "Changed AoA by (Finite Difference step)" << historyOutput_Map["CL_DRIVER_COMMAND"].value;
-      lastInnerIter = curInnerIter - 1;
     }
     else
       FixedCLSummary << "Changed AoA by" << historyOutput_Map["CL_DRIVER_COMMAND"].value;
     FixedCLSummary.PrintFooter();
     SetScreenHeader(config);
   }
 
-  else if (config->GetFinite_Difference_Mode() && historyOutput_Map["AOA"].value == historyOutput_Map["PREV_AOA"].value){
+  else if (config->GetFinite_Difference_Mode() && FixedCLEndFD()){
     FixedCLSummary.AddColumn("Fixed CL Mode (Finite Difference)", 40);
     FixedCLSummary.AddColumn("Value", 30);
     FixedCLSummary.SetAlign(PrintingToolbox::CTablePrinter::LEFT);
@@ -4276,6 +4275,20 @@ void CFlowOutput::SetFixedCLScreenOutput(const CConfig *config){
     }
     FixedCLSummary << "Delta CMz / Delta CL" << config->GetdCMz_dCL();
     FixedCLSummary.PrintFooter();
+  }
+}
+
+void CFlowOutput::SetFixedCLFiniteDifference(const CConfig *config){
+
+  /*--- This runs every iteration, independently of the screen output frequency, otherwise the finite
+   * difference step can end without writing dCL/dAlpha and dCX/dCL to the meta data file. ---*/
+
+  if (!config->GetFinite_Difference_Mode()) return;
+
+  if (FixedCLStartFD()){
+    lastInnerIter = curInnerIter - 1;
+  }
+  else if (FixedCLEndFD()){
     curInnerIter = lastInnerIter;
     WriteMetaData(config);
     curInnerIter = config->GetInnerIter();

SU2_CFD/src/output/CNEMOCompOutput.cpp

@@ -437,6 +437,10 @@ void CNEMOCompOutput::LoadHistoryData(CConfig *config, CGeometry *geometry, CSol
 
   SetAerodynamicCoefficients(config, NEMO_solver);
 
+  /*--- Fixed CL finite difference step, uses the AOA set above. ---*/
+
+  if (config->GetFixed_CL_Mode()) SetFixedCLFiniteDifference(config);
+
   SetHeatCoefficients(config, NEMO_solver);
 
   SetRotatingFrameCoefficients(NEMO_solver);