add save freq config option

Author: jtlau

Common/include/CConfig.hpp

@@ -1127,7 +1127,8 @@ class CConfig {
   bool libROM;                              /*!< \brief Toggle saving to libROM. */
   string libROMbase_FileName;               /*!< \brief Base filename for libROM file saving. */
   POD_KIND POD_Basis_Gen;                   /*!< \brief Type of POD basis generation (static or incremental). */
-  unsigned short maxBasisDim;               /*!< \brief Maximum number of POD basis dimensions. */
+  unsigned short maxBasisDim,               /*!< \brief Maximum number of POD basis dimensions. */
+  rom_save_freq;                            /*!< \brief Frequency of unsteady time steps to save. */
 
   /* other NEMO configure options*/
   unsigned short nSpecies,                  /*!< \brief No of species present in flow */
@@ -9322,4 +9323,9 @@ class CConfig {
    */
   unsigned short GetMax_BasisDim(void) const { return maxBasisDim; }
 
+  /*!
+   * \brief Get frequency of unsteady time steps to save (default: 1).
+   * \return Save frequency for unsteady time steps.
+   */
+  unsigned short GetRom_SaveFreq(void) const { return rom_save_freq; }
 };

Common/src/CConfig.cpp

@@ -2794,6 +2794,9 @@ void CConfig::SetConfig_Options() {
   /*!\brief MAX_BASIS_DIM \n DESCRIPTION: Maximum number of basis vectors.*/
   addUnsignedShortOption("MAX_BASIS_DIM", maxBasisDim, 100);
 
+  /*!\brief MAX_BASIS_DIM \n DESCRIPTION: Maximum number of basis vectors.*/
+  addUnsignedShortOption("ROM_SAVE_FREQ", rom_save_freq, 1);
+  
   /* END_CONFIG_OPTIONS */
 
 }

SU2_CFD/src/solvers/CSolver.cpp

@@ -4217,6 +4217,7 @@ void CSolver::SavelibROM(CSolver** solver, CGeometry *geometry, CConfig *config,
   const unsigned long TimeIter   = config->GetTimeIter();
   const unsigned long nTimeIter  = config->GetnTime_Iter();
   const int maxBasisDim          = config->GetMax_BasisDim();
+  const int save_freq            = config->GetRom_SaveFreq();
   int dim = int(nPointDomain * nVar);
   bool incremental = false;
 
@@ -4261,7 +4262,7 @@ void CSolver::SavelibROM(CSolver** solver, CGeometry *geometry, CConfig *config,
     f.close();
   }
 
-  if (unsteady) {
+  if (unsteady && (TimeIter % save_freq == 0)) {
     // give solution and time steps to libROM:
     double dt = config->GetDelta_UnstTime();
     double t =  config->GetCurrent_UnstTime();