Actual source code: plexfvm.c
1: #include <petsc/private/dmpleximpl.h>
2: #include <petscsf.h>
4: #include <petsc/private/petscfeimpl.h>
5: #include <petsc/private/petscfvimpl.h>
7: static PetscErrorCode DMPlexApplyLimiter_Internal(DM dm, DM dmCell, PetscLimiter lim, PetscInt dim, PetscInt dof, PetscInt cell, PetscInt field, PetscInt face, PetscInt fStart, PetscInt fEnd, PetscReal *cellPhi, const PetscScalar *x, const PetscScalar *cellgeom, const PetscFVCellGeom *cg, const PetscScalar *cx, const PetscScalar *cgrad)
8: {
9: const PetscInt *children;
10: PetscInt numChildren;
12: PetscFunctionBegin;
13: PetscCall(DMPlexGetTreeChildren(dm, face, &numChildren, &children));
14: if (numChildren) {
15: PetscInt c;
17: for (c = 0; c < numChildren; c++) {
18: PetscInt childFace = children[c];
20: if (childFace >= fStart && childFace < fEnd) PetscCall(DMPlexApplyLimiter_Internal(dm, dmCell, lim, dim, dof, cell, field, childFace, fStart, fEnd, cellPhi, x, cellgeom, cg, cx, cgrad));
21: }
22: } else {
23: PetscScalar *ncx;
24: PetscFVCellGeom *ncg;
25: const PetscInt *fcells;
26: PetscInt ncell, d;
27: PetscReal v[3];
29: PetscCall(DMPlexGetSupport(dm, face, &fcells));
30: ncell = cell == fcells[0] ? fcells[1] : fcells[0];
31: if (field >= 0) {
32: PetscCall(DMPlexPointLocalFieldRead(dm, ncell, field, x, &ncx));
33: } else {
34: PetscCall(DMPlexPointLocalRead(dm, ncell, x, &ncx));
35: }
36: PetscCall(DMPlexPointLocalRead(dmCell, ncell, cellgeom, &ncg));
37: DMPlex_WaxpyD_Internal(dim, -1, cg->centroid, ncg->centroid, v);
38: for (d = 0; d < dof; ++d) {
39: /* We use the symmetric slope limited form of Berger, Aftosmis, and Murman 2005 */
40: PetscReal denom = DMPlex_DotD_Internal(dim, &cgrad[d * dim], v);
41: PetscReal fact = denom == 0 ? 1.0e+30 : 1 / denom;
42: PetscReal phi, flim = 0.5 * PetscRealPart(ncx[d] - cx[d]) * fact;
44: PetscCall(PetscLimiterLimit(lim, flim, &phi));
45: cellPhi[d] = PetscMin(cellPhi[d], phi);
46: }
47: }
48: PetscFunctionReturn(PETSC_SUCCESS);
49: }
51: PetscErrorCode DMPlexReconstructGradients_Internal(DM dm, PetscFV fvm, PetscInt fStart, PetscInt fEnd, Vec faceGeometry, Vec cellGeometry, Vec locX, Vec grad)
52: {
53: DM dmFace, dmCell, dmGrad;
54: DMLabel ghostLabel;
55: PetscDS prob;
56: PetscLimiter lim;
57: const PetscScalar *facegeom, *cellgeom, *x;
58: PetscScalar *gr;
59: PetscReal *cellPhi;
60: PetscInt dim, face, cell, field, dof, cStart, cEnd, nFields;
62: PetscFunctionBegin;
63: PetscCall(DMGetDimension(dm, &dim));
64: PetscCall(DMGetDS(dm, &prob));
65: PetscCall(PetscDSGetNumFields(prob, &nFields));
66: PetscCall(PetscDSGetFieldIndex(prob, (PetscObject)fvm, &field));
67: PetscCall(PetscDSGetFieldSize(prob, field, &dof));
68: PetscCall(DMGetLabel(dm, "ghost", &ghostLabel));
69: PetscCall(PetscFVGetLimiter(fvm, &lim));
70: PetscCall(VecGetDM(faceGeometry, &dmFace));
71: PetscCall(VecGetArrayRead(faceGeometry, &facegeom));
72: PetscCall(VecGetDM(cellGeometry, &dmCell));
73: PetscCall(VecGetArrayRead(cellGeometry, &cellgeom));
74: PetscCall(VecGetArrayRead(locX, &x));
75: PetscCall(VecGetDM(grad, &dmGrad));
76: PetscCall(VecZeroEntries(grad));
77: PetscCall(VecGetArray(grad, &gr));
78: /* Reconstruct gradients */
79: for (face = fStart; face < fEnd; ++face) {
80: const PetscInt *cells;
81: PetscFVFaceGeom *fg;
82: PetscScalar *cx[2];
83: PetscScalar *cgrad[2];
84: PetscBool boundary;
85: PetscInt ghost, c, pd, d, numChildren, numCells;
87: PetscCall(DMLabelGetValue(ghostLabel, face, &ghost));
88: PetscCall(DMIsBoundaryPoint(dm, face, &boundary));
89: PetscCall(DMPlexGetTreeChildren(dm, face, &numChildren, NULL));
90: if (ghost >= 0 || boundary || numChildren) continue;
91: PetscCall(DMPlexGetSupportSize(dm, face, &numCells));
92: PetscCheck(numCells == 2, PETSC_COMM_SELF, PETSC_ERR_PLIB, "facet %" PetscInt_FMT " has %" PetscInt_FMT " support points: expected 2", face, numCells);
93: PetscCall(DMPlexGetSupport(dm, face, &cells));
94: PetscCall(DMPlexPointLocalRead(dmFace, face, facegeom, &fg));
95: for (c = 0; c < 2; ++c) {
96: if (nFields > 1) {
97: PetscCall(DMPlexPointLocalFieldRead(dm, cells[c], field, x, &cx[c]));
98: } else {
99: PetscCall(DMPlexPointLocalRead(dm, cells[c], x, &cx[c]));
100: }
101: PetscCall(DMPlexPointGlobalRef(dmGrad, cells[c], gr, &cgrad[c]));
102: }
103: for (pd = 0; pd < dof; ++pd) {
104: PetscScalar delta = cx[1][pd] - cx[0][pd];
106: for (d = 0; d < dim; ++d) {
107: if (cgrad[0]) cgrad[0][pd * dim + d] += fg->grad[0][d] * delta;
108: if (cgrad[1]) cgrad[1][pd * dim + d] -= fg->grad[1][d] * delta;
109: }
110: }
111: }
112: /* Limit interior gradients (using cell-based loop because it generalizes better to vector limiters) */
113: PetscCall(DMPlexGetSimplexOrBoxCells(dm, 0, &cStart, &cEnd));
114: PetscCall(DMGetWorkArray(dm, dof, MPIU_REAL, &cellPhi));
115: for (cell = (dmGrad && lim) ? cStart : cEnd; cell < cEnd; ++cell) {
116: const PetscInt *faces;
117: PetscScalar *cx;
118: PetscFVCellGeom *cg;
119: PetscScalar *cgrad;
120: PetscInt coneSize, f, pd, d;
122: PetscCall(DMPlexGetConeSize(dm, cell, &coneSize));
123: PetscCall(DMPlexGetCone(dm, cell, &faces));
124: if (nFields > 1) {
125: PetscCall(DMPlexPointLocalFieldRead(dm, cell, field, x, &cx));
126: } else {
127: PetscCall(DMPlexPointLocalRead(dm, cell, x, &cx));
128: }
129: PetscCall(DMPlexPointLocalRead(dmCell, cell, cellgeom, &cg));
130: PetscCall(DMPlexPointGlobalRef(dmGrad, cell, gr, &cgrad));
131: if (!cgrad) continue; /* Unowned overlap cell, we do not compute */
132: /* Limiter will be minimum value over all neighbors */
133: for (d = 0; d < dof; ++d) cellPhi[d] = PETSC_MAX_REAL;
134: for (f = 0; f < coneSize; ++f) PetscCall(DMPlexApplyLimiter_Internal(dm, dmCell, lim, dim, dof, cell, nFields > 1 ? field : -1, faces[f], fStart, fEnd, cellPhi, x, cellgeom, cg, cx, cgrad));
135: /* Apply limiter to gradient */
136: for (pd = 0; pd < dof; ++pd) /* Scalar limiter applied to each component separately */
137: for (d = 0; d < dim; ++d) cgrad[pd * dim + d] *= cellPhi[pd];
138: }
139: PetscCall(DMRestoreWorkArray(dm, dof, MPIU_REAL, &cellPhi));
140: PetscCall(VecRestoreArrayRead(faceGeometry, &facegeom));
141: PetscCall(VecRestoreArrayRead(cellGeometry, &cellgeom));
142: PetscCall(VecRestoreArrayRead(locX, &x));
143: PetscCall(VecRestoreArray(grad, &gr));
144: PetscFunctionReturn(PETSC_SUCCESS);
145: }
147: /*@
148: DMPlexReconstructGradientsFVM - reconstruct the gradient of a vector using a finite volume method.
150: Input Parameters:
151: + dm - the mesh
152: - locX - the local representation of the vector
154: Output Parameter:
155: . grad - the global representation of the gradient
157: Level: developer
159: .seealso: [](ch_unstructured), `DM`, `Vec`, `DMPlexGetGradientDM()`
160: @*/
161: PetscErrorCode DMPlexReconstructGradientsFVM(DM dm, Vec locX, Vec grad)
162: {
163: PetscDS prob;
164: PetscInt Nf, f, fStart, fEnd;
165: PetscBool useFVM = PETSC_FALSE;
166: PetscFV fvm = NULL;
167: Vec faceGeometryFVM, cellGeometryFVM;
168: PetscFVCellGeom *cgeomFVM = NULL;
169: PetscFVFaceGeom *fgeomFVM = NULL;
170: DM dmGrad = NULL;
172: PetscFunctionBegin;
173: PetscCall(DMGetDS(dm, &prob));
174: PetscCall(PetscDSGetNumFields(prob, &Nf));
175: for (f = 0; f < Nf; ++f) {
176: PetscObject obj;
177: PetscClassId id;
179: PetscCall(PetscDSGetDiscretization(prob, f, &obj));
180: PetscCall(PetscObjectGetClassId(obj, &id));
181: if (id == PETSCFV_CLASSID) {
182: useFVM = PETSC_TRUE;
183: fvm = (PetscFV)obj;
184: }
185: }
186: PetscCheck(useFVM, PetscObjectComm((PetscObject)dm), PETSC_ERR_SUP, "This dm does not have a finite volume discretization");
187: PetscCall(DMPlexGetDataFVM(dm, fvm, &cellGeometryFVM, &faceGeometryFVM, &dmGrad));
188: PetscCheck(dmGrad, PetscObjectComm((PetscObject)dm), PETSC_ERR_SUP, "This dm's finite volume discretization does not reconstruct gradients");
189: PetscCall(VecGetArrayRead(faceGeometryFVM, (const PetscScalar **)&fgeomFVM));
190: PetscCall(VecGetArrayRead(cellGeometryFVM, (const PetscScalar **)&cgeomFVM));
191: PetscCall(DMPlexGetHeightStratum(dm, 1, &fStart, &fEnd));
192: PetscCall(DMPlexReconstructGradients_Internal(dm, fvm, fStart, fEnd, faceGeometryFVM, cellGeometryFVM, locX, grad));
193: PetscFunctionReturn(PETSC_SUCCESS);
194: }