Added method to single-physics T/H driver to determine which calling …

…ranks access full T/H solution fields. Refs enrico-dev#15

include/enrico/heat_fluids_driver.h

@@ -15,6 +15,11 @@ class HeatFluidsDriver : public Driver {
 
   virtual ~HeatFluidsDriver() = default;
 
+  //! Whether the calling rank has access to the fields returned
+  //! by the 'temperature', 'density', and 'fluid_mask' methods
+  //! \return Whether calling rank has access
+  virtual bool has_coupling_data() const = 0;
+
   //! Get the temperature in each region
   //! \return Temperature in each region as [K]
   virtual xt::xtensor<double, 1> temperature() const = 0;

include/enrico/nek_driver.h

@@ -44,6 +44,10 @@ class NekDriver : public HeatFluidsDriver {
   //! initialization and finalization for each step.
   void solve_step() final;
 
+  //! Whether the calling rank has access to the full thermal-hydraulic solution field.
+  //! Only Nek's master rank has access to the global data; data on other ranks is empty
+  bool has_coupling_data() const final { return comm_.rank == 0; }
+
   xt::xtensor<double, 1> temperature() const final;
 
   xt::xtensor<double, 1> density() const final;

include/enrico/surrogate_heat_driver.h

@@ -21,6 +21,8 @@ class SurrogateHeatDriver : public HeatFluidsDriver {
   //! \param node  XML node containing settings for surrogate
   explicit SurrogateHeatDriver(MPI_Comm comm, double pressure_bc, pugi::xml_node node);
 
+  bool has_coupling_data() const final { return true; }
+
   //! Solves the heat-fluids surrogate solver
   void solve_step() final;
 

src/openmc_nek_driver.cpp

@@ -305,7 +305,7 @@ void OpenmcNekDriver::init_elem_fluid_mask()
     // On Nek's master rank, fm gets global data. On Nek's other ranks, fm is empty
     auto fm = nek_driver_->fluid_mask();
     // Initialize elem_fluid_mask_ on Nek's master rank only
-    if (nek_driver_->comm_.rank == 0) {
+    if (nek_driver_->has_coupling_data()) {
       elem_fluid_mask_ = fm;
     }
     // Since OpenMC's and Nek's master ranks are the same, we know that elem_fluid_mask_
@@ -418,7 +418,9 @@ void OpenmcNekDriver::update_density()
   if (nek_driver_->active()) {
     // On Nek's master rank, d gets global data. On Nek's other ranks, d is empty.
     auto d = nek_driver_->density();
-    if (nek_driver_->comm_.rank == 0) {
+
+    // Update elem_densities_ on Nek's master rank only.
+    if (nek_driver_->has_coupling_data()) {
       densities_ = d;
     }