[PNM] Add diffusive enthalpy transport

dumux/flux/porenetwork/fourierslaw.hh

@@ -26,13 +26,22 @@
 #define DUMUX_FLUX_PNM_FOURIERS_LAW_HH
 
 #include <dumux/common/math.hh>
+#include <dumux/flux/referencesystemformulation.hh>
+#include <type_traits>
 
 namespace Dumux::PoreNetwork {
 
+namespace Detail {
+
+struct NoDiffusionType {};
+
+} // end namespace Detail
+
  /*!
   * \ingroup PoreNetworkModels
   * \brief Specialization of Fourier's Law for the pore-network model.
   */
+template<class MolecularDiffusionType = Detail::NoDiffusionType>
 struct PNMFouriersLaw
 {
 
@@ -68,7 +77,41 @@ struct PNMFouriersLaw
             const Scalar gradT = deltaT/fluxVarsCache.throatLength();
 
             heatflux += thermalConductivity*gradT*area;
+
+            if constexpr (!std::is_same_v<MolecularDiffusionType, Detail::NoDiffusionType>)
+                heatflux += componentEnthalpyFlux_(problem, element, fvGeometry, elemVolVars, scvf, elemFluxVarsCache, phaseIdx);
+        }
+
+        return heatflux;
+    }
+
+private:
+    template<class Problem, class Element, class FVElementGeometry,
+             class ElementVolumeVariables, class ElementFluxVariablesCache>
+    static auto componentEnthalpyFlux_(const Problem& problem,
+                                       const Element& element,
+                                       const FVElementGeometry& fvGeometry,
+                                       const ElementVolumeVariables& elemVolVars,
+                                       const typename FVElementGeometry::SubControlVolumeFace& scvf,
+                                       const ElementFluxVariablesCache& elemFluxVarsCache,
+                                       const int phaseIdx)
+    {
+        using Scalar = typename ElementVolumeVariables::VolumeVariables::PrimaryVariables::value_type;
+        Scalar heatflux = 0.0;
+        using FluidSystem = typename ElementVolumeVariables::VolumeVariables::FluidSystem;
+        const auto diffusiveFlux = MolecularDiffusionType::flux(problem, element, fvGeometry, elemVolVars, scvf, phaseIdx, elemFluxVarsCache);
+        for (int compIdx = 0; compIdx < ElementVolumeVariables::VolumeVariables::numFluidComponents(); ++compIdx)
+        {
+            const bool insideIsUpstream = diffusiveFlux[compIdx] > 0.0;
+            const auto& upstreamVolVars = insideIsUpstream ? elemVolVars[scvf.insideScvIdx()] : elemVolVars[scvf.outsideScvIdx()];
+            const Scalar componentEnthalpy = FluidSystem::componentEnthalpy(upstreamVolVars.fluidState(), phaseIdx, compIdx);
+
+            if (MolecularDiffusionType::referenceSystemFormulation() == ReferenceSystemFormulation::massAveraged)
+                heatflux += diffusiveFlux[compIdx] * componentEnthalpy;
+            else
+                heatflux += diffusiveFlux[compIdx] * FluidSystem::molarMass(compIdx) * componentEnthalpy;
         }
+
         return heatflux;
     }
 };

dumux/porenetwork/1pnc/model.hh

@@ -242,5 +242,12 @@ struct ThermalConductivityModel<TypeTag, TTag::PNMOnePNCNI>
     using type = ThermalConductivityAverage<GetPropType<TypeTag, Properties::Scalar>>;
 }; //!< Use the average for effective conductivities
 
+// template<class TypeTag>
+// struct HeatConductionType<TypeTag, TTag::PNMOnePNCNI>
+// {
+//     TODO uncomment this as soon as there is a generalized approach for component enthalpies in all fluid systems
+//     using type = Dumux::PoreNetwork::PNMFouriersLaw<GetPropType<TypeTag, MolecularDiffusionType>>;
+// }; //!< Use Fourier's law and also consider enthalpy transport by molecular diffusion
+
 } // end namespace Dumux::Properties
 #endif

dumux/porenetwork/properties.hh

@@ -68,7 +68,7 @@ public:
 };
 
 template<class TypeTag>
-struct HeatConductionType<TypeTag, TTag::PoreNetworkModel> { using type = Dumux::PoreNetwork::PNMFouriersLaw; };
+struct HeatConductionType<TypeTag, TTag::PoreNetworkModel> { using type = Dumux::PoreNetwork::PNMFouriersLaw<>; };
 
 //! The labels
 template<class TypeTag>