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,
  8:                                                   PetscReal *cellPhi, const PetscScalar *x, const PetscScalar *cellgeom, const PetscFVCellGeom *cg, const PetscScalar *cx, const PetscScalar *cgrad)
  9: {
 10:   const PetscInt *children;
 11:   PetscInt        numChildren;

 13:   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) {
 21:         DMPlexApplyLimiter_Internal(dm,dmCell,lim,dim,dof,cell,field,childFace,fStart,fEnd,cellPhi,x,cellgeom,cg,cx,cgrad);
 22:       }
 23:     }
 24:   } else {
 25:     PetscScalar     *ncx;
 26:     PetscFVCellGeom *ncg;
 27:     const PetscInt  *fcells;
 28:     PetscInt         ncell, d;
 29:     PetscReal        v[3];

 31:     DMPlexGetSupport(dm, face, &fcells);
 32:     ncell = cell == fcells[0] ? fcells[1] : fcells[0];
 33:     if (field >= 0) {
 34:       DMPlexPointLocalFieldRead(dm, ncell, field, x, &ncx);
 35:     } else {
 36:       DMPlexPointLocalRead(dm, ncell, x, &ncx);
 37:     }
 38:     DMPlexPointLocalRead(dmCell, ncell, cellgeom, &ncg);
 39:     DMPlex_WaxpyD_Internal(dim, -1, cg->centroid, ncg->centroid, v);
 40:     for (d = 0; d < dof; ++d) {
 41:       /* We use the symmetric slope limited form of Berger, Aftosmis, and Murman 2005 */
 42:       PetscReal denom = DMPlex_DotD_Internal(dim, &cgrad[d * dim], v);
 43:       PetscReal phi, flim = 0.5 * PetscRealPart(ncx[d] - cx[d]) / denom;

 45:       PetscLimiterLimit(lim, flim, &phi);
 46:       cellPhi[d] = PetscMin(cellPhi[d], phi);
 47:     }
 48:   }
 49:   return 0;
 50: }

 52: PetscErrorCode DMPlexReconstructGradients_Internal(DM dm, PetscFV fvm, PetscInt fStart, PetscInt fEnd, Vec faceGeometry, Vec cellGeometry, Vec locX, Vec grad)
 53: {
 54:   DM                 dmFace, dmCell, dmGrad;
 55:   DMLabel            ghostLabel;
 56:   PetscDS            prob;
 57:   PetscLimiter       lim;
 58:   const PetscScalar *facegeom, *cellgeom, *x;
 59:   PetscScalar       *gr;
 60:   PetscReal         *cellPhi;
 61:   PetscInt           dim, face, cell, field, dof, cStart, cEnd, nFields;

 63:   DMGetDimension(dm, &dim);
 64:   DMGetDS(dm, &prob);
 65:   PetscDSGetNumFields(prob, &nFields);
 66:   PetscDSGetFieldIndex(prob, (PetscObject) fvm, &field);
 67:   PetscDSGetFieldSize(prob, field, &dof);
 68:   DMGetLabel(dm, "ghost", &ghostLabel);
 69:   PetscFVGetLimiter(fvm, &lim);
 70:   VecGetDM(faceGeometry, &dmFace);
 71:   VecGetArrayRead(faceGeometry, &facegeom);
 72:   VecGetDM(cellGeometry, &dmCell);
 73:   VecGetArrayRead(cellGeometry, &cellgeom);
 74:   VecGetArrayRead(locX, &x);
 75:   VecGetDM(grad, &dmGrad);
 76:   VecZeroEntries(grad);
 77:   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:     DMLabelGetValue(ghostLabel, face, &ghost);
 88:     DMIsBoundaryPoint(dm, face, &boundary);
 89:     DMPlexGetTreeChildren(dm, face, &numChildren, NULL);
 90:     if (ghost >= 0 || boundary || numChildren) continue;
 91:     DMPlexGetSupportSize(dm, face, &numCells);
 93:     DMPlexGetSupport(dm, face, &cells);
 94:     DMPlexPointLocalRead(dmFace, face, facegeom, &fg);
 95:     for (c = 0; c < 2; ++c) {
 96:       if (nFields > 1) {
 97:         DMPlexPointLocalFieldRead(dm, cells[c], field, x, &cx[c]);
 98:       } else {
 99:         DMPlexPointLocalRead(dm, cells[c], x, &cx[c]);
100:       }
101:       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:   DMPlexGetSimplexOrBoxCells(dm, 0, &cStart, &cEnd);
114:   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:     DMPlexGetConeSize(dm, cell, &coneSize);
123:     DMPlexGetCone(dm, cell, &faces);
124:     if (nFields > 1) {
125:       DMPlexPointLocalFieldRead(dm, cell, field, x, &cx);
126:     }
127:     else {
128:       DMPlexPointLocalRead(dm, cell, x, &cx);
129:     }
130:     DMPlexPointLocalRead(dmCell, cell, cellgeom, &cg);
131:     DMPlexPointGlobalRef(dmGrad, cell, gr, &cgrad);
132:     if (!cgrad) continue; /* Unowned overlap cell, we do not compute */
133:     /* Limiter will be minimum value over all neighbors */
134:     for (d = 0; d < dof; ++d) cellPhi[d] = PETSC_MAX_REAL;
135:     for (f = 0; f < coneSize; ++f) {
136:       DMPlexApplyLimiter_Internal(dm,dmCell,lim,dim,dof,cell,nFields > 1 ? field : -1,faces[f],fStart,fEnd,cellPhi,x,cellgeom,cg,cx,cgrad);
137:     }
138:     /* Apply limiter to gradient */
139:     for (pd = 0; pd < dof; ++pd)
140:       /* Scalar limiter applied to each component separately */
141:       for (d = 0; d < dim; ++d) cgrad[pd*dim+d] *= cellPhi[pd];
142:   }
143:   DMRestoreWorkArray(dm, dof, MPIU_REAL, &cellPhi);
144:   VecRestoreArrayRead(faceGeometry, &facegeom);
145:   VecRestoreArrayRead(cellGeometry, &cellgeom);
146:   VecRestoreArrayRead(locX, &x);
147:   VecRestoreArray(grad, &gr);
148:   return 0;
149: }

151: /*@
152:   DMPlexReconstructGradientsFVM - reconstruct the gradient of a vector using a finite volume method.

154:   Input Parameters:
155: + dm - the mesh
156: - locX - the local representation of the vector

158:   Output Parameter:
159: . grad - the global representation of the gradient

161:   Level: developer

163: .seealso: DMPlexGetGradientDM()
164: @*/
165: PetscErrorCode DMPlexReconstructGradientsFVM(DM dm, Vec locX, Vec grad)
166: {
167:   PetscDS          prob;
168:   PetscInt         Nf, f, fStart, fEnd;
169:   PetscBool        useFVM = PETSC_FALSE;
170:   PetscFV          fvm = NULL;
171:   Vec              faceGeometryFVM, cellGeometryFVM;
172:   PetscFVCellGeom  *cgeomFVM   = NULL;
173:   PetscFVFaceGeom  *fgeomFVM   = NULL;
174:   DM               dmGrad = NULL;

176:   DMGetDS(dm, &prob);
177:   PetscDSGetNumFields(prob, &Nf);
178:   for (f = 0; f < Nf; ++f) {
179:     PetscObject  obj;
180:     PetscClassId id;

182:     PetscDSGetDiscretization(prob, f, &obj);
183:     PetscObjectGetClassId(obj, &id);
184:     if (id == PETSCFV_CLASSID) {useFVM = PETSC_TRUE; fvm = (PetscFV) obj;}
185:   }
187:   DMPlexGetDataFVM(dm, fvm, &cellGeometryFVM, &faceGeometryFVM, &dmGrad);
189:   VecGetArrayRead(faceGeometryFVM, (const PetscScalar **) &fgeomFVM);
190:   VecGetArrayRead(cellGeometryFVM, (const PetscScalar **) &cgeomFVM);
191:   DMPlexGetHeightStratum(dm, 1, &fStart, &fEnd);
192:   DMPlexReconstructGradients_Internal(dm, fvm, fStart, fEnd, faceGeometryFVM, cellGeometryFVM, locX, grad);
193:   return 0;
194: }