Fix species unsteady restart (#2542)

* fix unsteady restart
Co-authored-by: Pedro Gomes <[email protected]>

Author: bigfooted

SU2_CFD/include/solvers/CScalarSolver.hpp

@@ -380,6 +380,12 @@ class CScalarSolver : public CSolver {
     return edgeMassFlux;
   }
 
+  /*!
+   * \brief Move solution to previous time levels (for restarts).
+   */
+  void PushSolutionBackInTime(unsigned long TimeIter, bool restart, CSolver*** solver_container,
+                              CGeometry** geometry, CConfig* config);
+
   /*!
    * \brief Gradient and Limiter computation.
    * \param[in] geometry - Geometrical definition of the problem.

SU2_CFD/include/solvers/CScalarSolver.inl

@@ -832,3 +832,33 @@ void CScalarSolver<VariableType>::SetResidual_DualTime(CGeometry* geometry, CSol
 
   }  // end dynamic grid
 }
+
+
+template <class VariableType>
+void CScalarSolver<VariableType>::PushSolutionBackInTime(unsigned long TimeIter, bool
+                                                         restart,CSolver*** solver_container,
+                                                         CGeometry** geometry, CConfig* config) {
+  const bool dual_time = config->GetTime_Marching() == TIME_MARCHING::DT_STEPPING_1ST ||
+                         config->GetTime_Marching() == TIME_MARCHING::DT_STEPPING_2ND;
+  const bool isRestartIter = restart && TimeIter == config->GetRestart_Iter();
+
+  /*--- The value of the solution for the first iteration of the dual time. ---*/
+
+  if (dual_time && (TimeIter == 0 || isRestartIter)) {
+    /*--- Push back the initial condition to previous solution containers
+     for a 1st-order restart or when simply initializing to freestream. ---*/
+
+    nodes->Set_Solution_time_n();
+    nodes->Set_Solution_time_n1();
+
+    if (isRestartIter && config->GetTime_Marching() == TIME_MARCHING::DT_STEPPING_2ND) {
+      /*--- Load an additional restart file for a 2nd-order restart ---*/
+
+      LoadRestart(geometry, solver_container, config, SU2_TYPE::Int(config->GetRestart_Iter()-1), true);
+
+      /*--- Push back this new solution to time level N. ---*/
+
+      nodes->Set_Solution_time_n();
+    }
+  }
+}

SU2_CFD/include/solvers/CSpeciesSolver.hpp

@@ -163,6 +163,18 @@ class CSpeciesSolver : public CScalarSolver<CSpeciesVariable> {
   void Source_Residual(CGeometry* geometry, CSolver** solver_container, CNumerics** numerics_container, CConfig* config,
                        unsigned short iMesh) override;
 
+  /*!
+   * \brief Set the initial condition for the Species transport problem.
+   * \param[in] geometry - Geometrical definition of the problem.
+   * \param[in] solver_container - Container with all the solutions.
+   * \param[in] config - Definition of the particular problem.
+   * \param[in] TimeIter - Time iteration.
+   */
+  void SetInitialCondition(CGeometry **geometry,
+                           CSolver ***solver_container,
+                           CConfig *config,
+                           unsigned long TimeIter) override;
+
   /*!
    * \brief Impose the fluid interface boundary condition using tranfer data.
    * \param[in] geometry - Geometrical definition of the problem.

SU2_CFD/src/solvers/CSpeciesFlameletSolver.cpp

@@ -152,9 +152,9 @@ void CSpeciesFlameletSolver::Preprocessing(CGeometry* geometry, CSolver** solver
 
 void CSpeciesFlameletSolver::SetInitialCondition(CGeometry** geometry, CSolver*** solver_container, CConfig* config,
                                                  unsigned long ExtIter) {
-  const bool Restart = (config->GetRestart() || config->GetRestart_Flow());
+  const bool restart = (config->GetRestart() || config->GetRestart_Flow());
 
-  if ((!Restart) && ExtIter == 0) {
+  if ((!restart) && ExtIter == 0) {
     if (rank == MASTER_NODE) {
       cout << "Initializing progress variable and total enthalpy (using temperature)" << endl;
     }
@@ -200,6 +200,7 @@ void CSpeciesFlameletSolver::SetInitialCondition(CGeometry** geometry, CSolver**
         default:
           break;
       }
+
     }
 
     CFluidModel* fluid_model_local;
@@ -311,6 +312,9 @@ void CSpeciesFlameletSolver::SetInitialCondition(CGeometry** geometry, CSolver**
              << n_not_iterated_global << " !!!" << endl;
     }
   }
+
+  /*--- All the unsteady initialization ---*/
+  PushSolutionBackInTime(ExtIter, restart, solver_container, geometry, config);
 }
 
 void CSpeciesFlameletSolver::SetPreconditioner(CGeometry* geometry, CSolver** solver_container, CConfig* config) {

SU2_CFD/src/solvers/CSpeciesSolver.cpp

@@ -570,3 +570,10 @@ void CSpeciesSolver::Source_Residual(CGeometry *geometry, CSolver **solver_conta
   }
 
 }
+
+void CSpeciesSolver::SetInitialCondition(CGeometry **geometry, CSolver ***solver_container, CConfig *config, unsigned long TimeIter) {
+
+  const bool restart = config->GetRestart() || config->GetRestart_Flow();
+
+  PushSolutionBackInTime(TimeIter, restart, solver_container, geometry, config);
+}