Actual source code: ex21.c


  2: static char help[] = "DMSwarm-PIC demonstator of advecting points within cell DM defined by a DA or PLEX object \n\
  3: Options: \n\
  4: -ppcell   : Number of times to sub-divide the reference cell when layout the initial particle coordinates \n\
  5: -meshtype : 0 ==> DA , 1 ==> PLEX \n\
  6: -nt       : Number of timestep to perform \n\
  7: -view     : Write out initial condition and time dependent data \n";

  9: #include <petsc.h>
 10: #include <petscdm.h>
 11: #include <petscdmda.h>
 12: #include <petscdmswarm.h>

 14: PetscErrorCode pic_advect(PetscInt ppcell, PetscInt meshtype)
 15: {
 16:   const PetscInt dim = 2;
 17:   DM             celldm, swarm;
 18:   PetscInt       tk, nt = 200;
 19:   PetscBool      view = PETSC_FALSE;
 20:   Vec           *pfields;
 21:   PetscReal      minradius;
 22:   PetscReal      dt;
 23:   PetscReal      vel[]        = {1.0, 0.16};
 24:   const char    *fieldnames[] = {"phi"};
 25:   PetscViewer    viewer;

 27:   PetscFunctionBegin;
 28:   PetscCall(PetscOptionsGetBool(NULL, NULL, "-view", &view, NULL));
 29:   PetscCall(PetscOptionsGetInt(NULL, NULL, "-nt", &nt, NULL));

 31:   /* Create the background cell DM */
 32:   if (meshtype == 0) { /* DA */
 33:     PetscInt nxy;
 34:     PetscInt dof           = 1;
 35:     PetscInt stencil_width = 1;

 37:     PetscCall(PetscPrintf(PETSC_COMM_WORLD, "Mesh type: DMDA\n"));
 38:     nxy = 33;
 39:     PetscCall(DMDACreate2d(PETSC_COMM_WORLD, DM_BOUNDARY_NONE, DM_BOUNDARY_NONE, DMDA_STENCIL_BOX, nxy, nxy, PETSC_DECIDE, PETSC_DECIDE, dof, stencil_width, NULL, NULL, &celldm));

 41:     PetscCall(DMDASetElementType(celldm, DMDA_ELEMENT_Q1));

 43:     PetscCall(DMSetFromOptions(celldm));

 45:     PetscCall(DMSetUp(celldm));

 47:     PetscCall(DMDASetUniformCoordinates(celldm, 0.0, 1.0, 0.0, 1.0, 0.0, 1.5));

 49:     minradius = 1.0 / ((PetscReal)(nxy - 1));

 51:     PetscCall(PetscPrintf(PETSC_COMM_WORLD, "DA(minradius) %1.4e\n", (double)minradius));
 52:   }

 54:   if (meshtype == 1) { /* PLEX */
 55:     DM           distributedMesh = NULL;
 56:     PetscInt     numComp[]       = {1};
 57:     PetscInt     numDof[]        = {1, 0, 0}; /* vert, edge, cell */
 58:     PetscInt     faces[]         = {1, 1, 1};
 59:     PetscInt     numBC           = 0;
 60:     PetscSection section;
 61:     Vec          cellgeom = NULL;
 62:     Vec          facegeom = NULL;

 64:     PetscCall(PetscPrintf(PETSC_COMM_WORLD, "Mesh type: DMPLEX\n"));
 65:     PetscCall(DMPlexCreateBoxMesh(PETSC_COMM_WORLD, dim, PETSC_TRUE, faces, NULL, NULL, PETSC_TRUE, &celldm));

 67:     /* Distribute mesh over processes */
 68:     PetscCall(DMPlexDistribute(celldm, 0, NULL, &distributedMesh));
 69:     if (distributedMesh) {
 70:       PetscCall(DMDestroy(&celldm));
 71:       celldm = distributedMesh;
 72:     }

 74:     PetscCall(DMSetFromOptions(celldm));

 76:     PetscCall(DMPlexCreateSection(celldm, NULL, numComp, numDof, numBC, NULL, NULL, NULL, NULL, &section));
 77:     PetscCall(DMSetLocalSection(celldm, section));

 79:     PetscCall(DMSetUp(celldm));

 81:     /* Calling DMPlexComputeGeometryFVM() generates the value returned by DMPlexGetMinRadius() */
 82:     PetscCall(DMPlexComputeGeometryFVM(celldm, &cellgeom, &facegeom));
 83:     PetscCall(DMPlexGetMinRadius(celldm, &minradius));
 84:     PetscCall(PetscPrintf(PETSC_COMM_WORLD, "PLEX(minradius) %1.4e\n", (double)minradius));
 85:     PetscCall(VecDestroy(&cellgeom));
 86:     PetscCall(VecDestroy(&facegeom));
 87:     PetscCall(PetscSectionDestroy(&section));
 88:   }

 90:   /* Create the DMSwarm */
 91:   PetscCall(DMCreate(PETSC_COMM_WORLD, &swarm));
 92:   PetscCall(DMSetType(swarm, DMSWARM));
 93:   PetscCall(DMSetDimension(swarm, dim));

 95:   /* Configure swarm to be of type PIC */
 96:   PetscCall(DMSwarmSetType(swarm, DMSWARM_PIC));
 97:   PetscCall(DMSwarmSetCellDM(swarm, celldm));

 99:   /* Register two scalar fields within the DMSwarm */
100:   PetscCall(DMSwarmRegisterPetscDatatypeField(swarm, "phi", 1, PETSC_REAL));
101:   PetscCall(DMSwarmRegisterPetscDatatypeField(swarm, "region", 1, PETSC_REAL));
102:   PetscCall(DMSwarmFinalizeFieldRegister(swarm));

104:   /* Set initial local sizes of the DMSwarm with a buffer length of zero */
105:   PetscCall(DMSwarmSetLocalSizes(swarm, 4, 0));

107:   /* Insert swarm coordinates cell-wise */
108:   /*PetscCall(DMSwarmInsertPointsUsingCellDM(swarm,DMSWARMPIC_LAYOUT_REGULAR,ppcell));*/
109:   PetscCall(DMSwarmInsertPointsUsingCellDM(swarm, DMSWARMPIC_LAYOUT_SUBDIVISION, ppcell));

111:   /* Define initial conditions for th swarm fields "phi" and "region" */
112:   {
113:     PetscReal *s_coor, *s_phi, *s_region;
114:     PetscInt   npoints, p;

116:     PetscCall(DMSwarmGetLocalSize(swarm, &npoints));
117:     PetscCall(DMSwarmGetField(swarm, DMSwarmPICField_coor, NULL, NULL, (void **)&s_coor));
118:     PetscCall(DMSwarmGetField(swarm, "phi", NULL, NULL, (void **)&s_phi));
119:     PetscCall(DMSwarmGetField(swarm, "region", NULL, NULL, (void **)&s_region));
120:     for (p = 0; p < npoints; p++) {
121:       PetscReal pos[2];
122:       pos[0] = s_coor[2 * p + 0];
123:       pos[1] = s_coor[2 * p + 1];

125:       s_region[p] = 1.0;
126:       s_phi[p]    = 1.0 + PetscExpReal(-200.0 * ((pos[0] - 0.5) * (pos[0] - 0.5) + (pos[1] - 0.5) * (pos[1] - 0.5)));
127:     }
128:     PetscCall(DMSwarmRestoreField(swarm, "region", NULL, NULL, (void **)&s_region));
129:     PetscCall(DMSwarmRestoreField(swarm, "phi", NULL, NULL, (void **)&s_phi));
130:     PetscCall(DMSwarmRestoreField(swarm, DMSwarmPICField_coor, NULL, NULL, (void **)&s_coor));
131:   }

133:   /* Project initial value of phi onto the mesh */
134:   PetscCall(DMSwarmProjectFields(swarm, 1, fieldnames, &pfields, PETSC_FALSE));

136:   if (view) {
137:     /* View swarm all swarm fields using data type PETSC_REAL */
138:     PetscCall(DMSwarmViewXDMF(swarm, "ic_dms.xmf"));

140:     /* View projected swarm field "phi" */
141:     PetscCall(PetscViewerCreate(PETSC_COMM_WORLD, &viewer));
142:     PetscCall(PetscViewerSetType(viewer, PETSCVIEWERVTK));
143:     PetscCall(PetscViewerFileSetMode(viewer, FILE_MODE_WRITE));
144:     if (meshtype == 0) { /* DA */
145:       PetscCall(PetscViewerFileSetName(viewer, "ic_dmda.vts"));
146:       PetscCall(VecView(pfields[0], viewer));
147:     }
148:     if (meshtype == 1) { /* PLEX */
149:       PetscCall(PetscViewerFileSetName(viewer, "ic_dmplex.vtk"));
150:       PetscCall(DMView(celldm, viewer));
151:       PetscCall(VecView(pfields[0], viewer));
152:     }
153:     PetscCall(PetscViewerDestroy(&viewer));
154:   }

156:   PetscCall(DMView(celldm, PETSC_VIEWER_STDOUT_WORLD));
157:   PetscCall(DMView(swarm, PETSC_VIEWER_STDOUT_WORLD));

159:   dt = 0.5 * minradius / PetscSqrtReal(vel[0] * vel[0] + vel[1] * vel[1]);
160:   for (tk = 1; tk <= nt; tk++) {
161:     PetscReal *s_coor;
162:     PetscInt   npoints, p;

164:     PetscCall(PetscPrintf(PETSC_COMM_WORLD, "[step %" PetscInt_FMT "]\n", tk));
165:     /* advect with analytic prescribed (constant) velocity field */
166:     PetscCall(DMSwarmGetLocalSize(swarm, &npoints));
167:     PetscCall(DMSwarmGetField(swarm, DMSwarmPICField_coor, NULL, NULL, (void **)&s_coor));
168:     for (p = 0; p < npoints; p++) {
169:       s_coor[2 * p + 0] += dt * vel[0];
170:       s_coor[2 * p + 1] += dt * vel[1];
171:     }
172:     PetscCall(DMSwarmRestoreField(swarm, DMSwarmPICField_coor, NULL, NULL, (void **)&s_coor));

174:     PetscCall(DMSwarmMigrate(swarm, PETSC_TRUE));

176:     /* Ad-hoc cell filling algorithm */
177:     /*
178:        The injection frequency is chosen for default DA case.
179:        They will likely not be appropriate for the general case using an unstructure PLEX mesh.
180:     */
181:     if (tk % 10 == 0) {
182:       PetscReal dx              = 1.0 / 32.0;
183:       PetscInt  npoints_dir_x[] = {32, 1};
184:       PetscReal min[2], max[2];

186:       min[0] = 0.5 * dx;
187:       max[0] = 0.5 * dx + 31.0 * dx;
188:       min[1] = 0.5 * dx;
189:       max[1] = 0.5 * dx;
190:       PetscCall(DMSwarmSetPointsUniformCoordinates(swarm, min, max, npoints_dir_x, ADD_VALUES));
191:     }
192:     if (tk % 2 == 0) {
193:       PetscReal dx              = 1.0 / 32.0;
194:       PetscInt  npoints_dir_y[] = {2, 31};
195:       PetscReal min[2], max[2];

197:       min[0] = 0.05 * dx;
198:       max[0] = 0.5 * dx;
199:       min[1] = 0.5 * dx;
200:       max[1] = 0.5 * dx + 31.0 * dx;
201:       PetscCall(DMSwarmSetPointsUniformCoordinates(swarm, min, max, npoints_dir_y, ADD_VALUES));
202:     }

204:     /* Project swarm field "phi" onto the cell DM */
205:     PetscCall(DMSwarmProjectFields(swarm, 1, fieldnames, &pfields, PETSC_TRUE));

207:     if (view) {
208:       PetscViewer viewer;
209:       char        fname[PETSC_MAX_PATH_LEN];

211:       /* View swarm fields */
212:       PetscCall(PetscSNPrintf(fname, PETSC_MAX_PATH_LEN - 1, "step%.4" PetscInt_FMT "_dms.xmf", tk));
213:       PetscCall(DMSwarmViewXDMF(swarm, fname));

215:       /* View projected field */
216:       PetscCall(PetscViewerCreate(PETSC_COMM_WORLD, &viewer));
217:       PetscCall(PetscViewerSetType(viewer, PETSCVIEWERVTK));
218:       PetscCall(PetscViewerFileSetMode(viewer, FILE_MODE_WRITE));

220:       if (meshtype == 0) { /* DA */
221:         PetscCall(PetscSNPrintf(fname, PETSC_MAX_PATH_LEN - 1, "step%.4" PetscInt_FMT "_dmda.vts", tk));
222:         PetscCall(PetscViewerFileSetName(viewer, fname));
223:         PetscCall(VecView(pfields[0], viewer));
224:       }
225:       if (meshtype == 1) { /* PLEX */
226:         PetscCall(PetscSNPrintf(fname, PETSC_MAX_PATH_LEN - 1, "step%.4" PetscInt_FMT "_dmplex.vtk", tk));
227:         PetscCall(PetscViewerFileSetName(viewer, fname));
228:         PetscCall(DMView(celldm, viewer));
229:         PetscCall(VecView(pfields[0], viewer));
230:       }
231:       PetscCall(PetscViewerDestroy(&viewer));
232:     }
233:   }
234:   PetscCall(VecDestroy(&pfields[0]));
235:   PetscCall(PetscFree(pfields));
236:   PetscCall(DMDestroy(&celldm));
237:   PetscCall(DMDestroy(&swarm));

239:   PetscFunctionReturn(PETSC_SUCCESS);
240: }

242: int main(int argc, char **args)
243: {
244:   PetscInt ppcell   = 1;
245:   PetscInt meshtype = 0;

247:   PetscFunctionBeginUser;
248:   PetscCall(PetscInitialize(&argc, &args, (char *)0, help));
249:   PetscCall(PetscOptionsGetInt(NULL, NULL, "-ppcell", &ppcell, NULL));
250:   PetscCall(PetscOptionsGetInt(NULL, NULL, "-meshtype", &meshtype, NULL));
251:   PetscCheck(meshtype <= 1, PETSC_COMM_WORLD, PETSC_ERR_USER, "-meshtype <value> must be 0 or 1");

253:   PetscCall(pic_advect(ppcell, meshtype));

255:   PetscCall(PetscFinalize());
256:   return 0;
257: }