Add EK species/container tau cross-check

src/script_interface/walberla/EKContainer.hpp

@@ -103,6 +103,12 @@ class EKContainer : public ObjectList<EKSpecies, EK::Container> {
         throw std::runtime_error(
             "Cannot mix single and double precision kernels");
       }
+      auto const tau_container = m_ek_container->get_tau();
+      auto const tau_species = get_value<double>(obj_ptr->get_parameter("tau"));
+      if (tau_species != tau_container) {
+        throw std::runtime_error(
+            "EK species and EK container must have the same tau");
+      }
       ek_throw_if_expired(obj_ptr->get_mpi_cart_comm_observer());
       m_ek_container->add(obj_ptr->get_ekinstance());
     });

testsuite/python/ek_interface.py

@@ -332,6 +332,10 @@ def test_ek_container_exceptions(self):
             self.system.ekcontainer.solver,
             ek_solver_incompatible)
         self.assertEqual(len(self.system.ekcontainer), 1)
+        # the tau value must match for units conversion
+        with self.assertRaisesRegex(RuntimeError, "EK species and EK container must have the same tau"):
+            self.system.ekcontainer.add(self.make_default_ek_species(tau=200.))
+        self.assertEqual(len(self.system.ekcontainer), 1)
 
     def test_ek_solver_exceptions(self):
         ek_solver = self.system.ekcontainer.solver