Add struct variable to cds solver to inform it that temperature is on…

…e of the passive scalars. Refs Nek5000#170

src/core/cds.h

@@ -23,6 +23,10 @@ typedef struct
   int NVfields;            // Number of velocity fields
   int NSfields;            // Number of scalar fields
 
+  // Whether one of the scalars represents temperature; if temperature is a passive
+  // scalar, then temperature is the first passive scalar
+  bool temperature_solution;
+
   setupAide options;
 
   oogs_t *gsh, *gshT;

src/core/parReader.cpp

@@ -521,6 +521,7 @@ libParanumal::setupAide parRead(std::string &setupFile, MPI_Comm comm)
   int nscal = 0;
   int isStart = 0;
   if(ini.sections.count("temperature")) {
+    options.setArgs("TEMPERATURE_SOLUTION", "TRUE");
     nscal++;
     isStart++;
 
@@ -581,6 +582,8 @@ libParanumal::setupAide parRead(std::string &setupFile, MPI_Comm comm)
       }
     }
   }
+  else
+    options.setArgs("TEMPERATURE_SOLUTION", "FALSE");
 
   //
   for (auto & sec : ini.sections) {

src/nekrs.cpp

@@ -99,6 +99,12 @@ void setup(MPI_Comm comm_in, int buildOnly, int sizeTarget,
   // init solver
   ins = insSetup(comm, device, options, buildOnly);
 
+  // tell the cds solver whether one of the passive scalars represents temperature
+  if (ins->Nscalar) {
+    auto temp = options.getArgs("TEMPERATURE_SOLUTION");
+    ins->cds->temperature_solution = temp == "TRUE" ? true : false;
+  }
+
   // set initial condition
   int readRestartFile;
   options.getArgs("RESTART FROM FILE", readRestartFile);
@@ -221,6 +227,17 @@ void printRuntimeStatistics()
 {
   timer::printRunStat();
 }
+
+const bool hasTemperatureSolution()
+{
+  // if there are scalars, check the convection-diffusion solver for temperature;
+  // otherwise, a lack of scalars means that there is definitely no temperature
+  if (ins->Nscalar)
+    return ins->cds->temperature_solution;
+  else
+    return false;
+}
+
 } // namespace
 
 static void dryRun(libParanumal::setupAide &options, int npTarget)

src/nekrs.hpp

@@ -16,6 +16,7 @@ void udfExecuteStep(double time, int tstep, int isOutputStep);
 void nekOutfld(void);
 void nekUserchk(void);
 void printRuntimeStatistics(void);
+const bool hasTemperatureSolution(void);
 
 const double dt(void);
 const int outputStep(void);