preliminary refactoring

applications/solvers/dfLowMachFoam/UEqn.H

@@ -101,7 +101,7 @@ end1 = std::clock();
     boundary_pressure_init, boundary_velocity_init, boundary_nuEff_init, boundary_rho_init);
     UEqn_GPU.fvc_grad(&p[0]);
     UEqn_GPU.fvc_grad_vector();
-    UEqn_GPU.divDevRhoReff();
+    UEqn_GPU.dev2T();
     UEqn_GPU.fvc_div_tensor(&nuEff[0]);
     UEqn_GPU.fvm_laplacian();
     end1 = std::clock();

applications/solvers/dfLowMachFoam/createdfSolver.H

@@ -28,8 +28,10 @@ int num_boundary_cells;
 string settingPath;
 settingPath = CanteraTorchProperties.subDict("AmgxSettings").lookupOrDefault("UEqnSettingPath", string(""));
 
-dfMatrix UEqn_GPU(num_surfaces, num_cells, num_boundary_faces, num_boundary_cells, &neighbour[0], &owner[0], &mesh.V()[0], &mesh.surfaceInterpolation::weights()[0], 
-&mesh.Sf()[0][0], &mesh.magSf()[0], &mesh.nonOrthDeltaCoeffs()[0], boundary_face_vector_init, boundary_face_init, boundary_deltaCoeffs_init, boundaryCellIndex, "dDDI", settingPath);
+dfMatrixDataBase dfDataBase(num_surfaces, num_cells, num_boundary_faces, num_boundary_cells, &neighbour[0], &owner[0], &mesh.V()[0], &mesh.surfaceInterpolation::weights()[0], 
+&mesh.Sf()[0][0], &mesh.magSf()[0], &mesh.nonOrthDeltaCoeffs()[0], boundary_face_vector_init, boundary_face_init, boundary_deltaCoeffs_init, boundaryCellIndex);
+
+dfUEqn UEqn_GPU(dfDataBase, "dDDI", settingPath);
 
 double *ueqn_internalCoeffs_init, *ueqn_boundaryCoeffs_init, *boundary_pressure_init, *boundary_velocity_init,
     *boundary_nuEff_init, *boundary_rho_init, *ueqn_laplac_internalCoeffs_init, *ueqn_laplac_boundaryCoeffs_init;

applications/solvers/dfLowMachFoam/dfLowMachFoam.C

@@ -59,7 +59,7 @@ Description
 #include "basicThermo.H"
 #include "CombustionModel.H"
 
-#include "dfMatrix.H"
+#include "dfUEqn.H"
 #include <cuda_runtime.h>
 #include <thread>
 

src_gpu/CMakeLists.txt

@@ -18,7 +18,7 @@ include_directories(
     $ENV{AMGX_DIR}/include
 )
 
-add_library(${PROJECT_NAME} SHARED dfMatrix.cu AmgXSolver.cu)
+add_library(${PROJECT_NAME} SHARED dfUEqn.cu AmgXSolver.cu)
 
 target_link_libraries(${PROJECT_NAME}
     ${MPI_LIBRARIES}

src_gpu/GPUMesh.H

@@ -0,0 +1,23 @@
+#include <iostream>
+
+class GPUMesh
+{
+public:
+    int num_cells;
+    int num_faces;
+    int boundary_cells;
+    //... all variables needed to upload once
+
+public:
+    GPUMesh();
+    ~GPUMesh();
+};
+
+GPUMesh::GPUMesh()
+{
+    // same to the constructor of dfMatrix.C
+}
+
+GPUMesh::~GPUMesh()
+{
+}

src_gpu/GPUfield.H

@@ -0,0 +1,57 @@
+/*
+GPU field
+UEqn
+GPUField
+rho_old, rho_new, vector_old, phi, p, nuEff, 
+p_bou, vector_old_bou, nuEff_bou, rho_new_bou, 
+ueqn_internalCoeffs, ueqn_boundaryCoeffs_init, ueqn_laplac_internalCoeffs_init, ueqn_laplac_boundaryCoeffs_init
+1. initialize a map
+2. implement methods to construct GPU pointer and return GPU pointer
+
+fvm__ddt(UEqn, rho, U)
+{
+    rho.oldtime()
+    rho.
+}
+*/
+#include <iostream>
+#include <unordered_map>
+
+#define TOSTRING(x) #x
+
+struct GPUField {
+    double* cur_internal;
+    double* cur_boundary;
+    double* old_internal;
+    double* old_boundary;
+};
+std::unordered_map<std::string, GPUField> GPUFields;
+
+// initialize: cudaMalloc, conducted at begining
+void initialize(std::string U, std::string p, std::string phi);
+// Q: 
+// 1. consider the different sizes bettween face values and cell values
+// 2. not all variables need all these four terms
+
+// update at the end of this time step
+// move current pointer as oldTime pointer
+void update();
+
+template<class Type, template<class> class PatchField, class GeoMesh>
+double* cur_internal(Foam::GeometryField<Type, PatchField, GeoMesh> var)
+{
+    if (!GPUFields[TOSTRING(var)].cur_internal) {
+        // 1. cudaMemcopy current internal field
+    }
+    return GPUFields[TOSTRING(var)].cur_internal;
+}
+
+template<class Type, template<class> class PatchField, class GeoMesh>
+double* cur_boundary(Foam::GeometryField<Type, PatchField, GeoMesh> var);
+
+template<class Type, template<class> class PatchField, class GeoMesh>
+double* old_internal(Foam::GeometryField<Type, PatchField, GeoMesh> var);
+
+template<class Type, template<class> class PatchField, class GeoMesh>
+double* old_boundary(Foam::GeometryField<Type, PatchField, GeoMesh> var);
+

src_gpu/GPUfield.cpp

@@ -0,0 +1,18 @@
+/*
+GPU field
+UEqn
+GPUField
+rho_old, rho_new, vector_old, phi, p, nuEff, 
+p_bou, vector_old_bou, nuEff_bou, rho_new_bou, 
+ueqn_internalCoeffs, ueqn_boundaryCoeffs_init, ueqn_laplac_internalCoeffs_init, ueqn_laplac_boundaryCoeffs_init
+1. initialize a map
+2. implement methods to construct GPU pointer and return GPU pointer
+
+fvm__ddt(UEqn, rho, U)
+{
+    rho.oldtime()
+    rho.
+}
+*/
+#include <stdio.h>
+