Actual source code: ex23.c
1: static char help[] = "Poisson Problem with a split domain.\n\
2: We solve the Poisson problem in two halves of a domain.\n\
3: In one half, we include an additional field.\n\n\n";
5: #include <petscdmplex.h>
6: #include <petscsnes.h>
7: #include <petscds.h>
8: #include <petscconvest.h>
10: typedef struct {
11: PetscInt dummy;
12: } AppCtx;
14: static PetscErrorCode quad_u(PetscInt dim, PetscReal time, const PetscReal x[], PetscInt Nc, PetscScalar *u, void *ctx)
15: {
16: u[0] = x[0] * x[0] + x[1] * x[1];
17: return PETSC_SUCCESS;
18: }
20: static PetscErrorCode quad_p(PetscInt dim, PetscReal time, const PetscReal x[], PetscInt Nc, PetscScalar *u, void *ctx)
21: {
22: u[0] = 2.0;
23: return PETSC_SUCCESS;
24: }
26: static void f0_quad_u(PetscInt dim, PetscInt Nf, PetscInt NfAux, const PetscInt uOff[], const PetscInt uOff_x[], const PetscScalar u[], const PetscScalar u_t[], const PetscScalar u_x[], const PetscInt aOff[], const PetscInt aOff_x[], const PetscScalar a[], const PetscScalar a_t[], const PetscScalar a_x[], PetscReal t, const PetscReal x[], PetscInt numConstants, const PetscScalar constants[], PetscScalar f0[])
27: {
28: PetscInt d;
29: for (d = 0; d < dim; ++d) f0[0] += 2.0;
30: }
32: static void f0_quad_p(PetscInt dim, PetscInt Nf, PetscInt NfAux, const PetscInt uOff[], const PetscInt uOff_x[], const PetscScalar u[], const PetscScalar u_t[], const PetscScalar u_x[], const PetscInt aOff[], const PetscInt aOff_x[], const PetscScalar a[], const PetscScalar a_t[], const PetscScalar a_x[], PetscReal t, const PetscReal x[], PetscInt numConstants, const PetscScalar constants[], PetscScalar f0[])
33: {
34: f0[0] = u[uOff[1]] - 2.0;
35: }
37: static void f1_u(PetscInt dim, PetscInt Nf, PetscInt NfAux, const PetscInt uOff[], const PetscInt uOff_x[], const PetscScalar u[], const PetscScalar u_t[], const PetscScalar u_x[], const PetscInt aOff[], const PetscInt aOff_x[], const PetscScalar a[], const PetscScalar a_t[], const PetscScalar a_x[], PetscReal t, const PetscReal x[], PetscInt numConstants, const PetscScalar constants[], PetscScalar f1[])
38: {
39: PetscInt d;
40: for (d = 0; d < dim; ++d) f1[d] = u_x[d];
41: }
43: static void g3_uu(PetscInt dim, PetscInt Nf, PetscInt NfAux, const PetscInt uOff[], const PetscInt uOff_x[], const PetscScalar u[], const PetscScalar u_t[], const PetscScalar u_x[], const PetscInt aOff[], const PetscInt aOff_x[], const PetscScalar a[], const PetscScalar a_t[], const PetscScalar a_x[], PetscReal t, PetscReal u_tShift, const PetscReal x[], PetscInt numConstants, const PetscScalar constants[], PetscScalar g3[])
44: {
45: PetscInt d;
46: for (d = 0; d < dim; ++d) g3[d * dim + d] = 1.0;
47: }
49: static void g0_pp(PetscInt dim, PetscInt Nf, PetscInt NfAux, const PetscInt uOff[], const PetscInt uOff_x[], const PetscScalar u[], const PetscScalar u_t[], const PetscScalar u_x[], const PetscInt aOff[], const PetscInt aOff_x[], const PetscScalar a[], const PetscScalar a_t[], const PetscScalar a_x[], PetscReal t, PetscReal u_tShift, const PetscReal x[], PetscInt numConstants, const PetscScalar constants[], PetscScalar g0[])
50: {
51: g0[0] = 1.0;
52: }
54: static PetscErrorCode DivideDomain(DM dm, AppCtx *user)
55: {
56: DMLabel top, bottom;
57: PetscReal low[3], high[3], midy;
58: PetscInt cStart, cEnd, c;
60: PetscFunctionBeginUser;
61: PetscCall(DMCreateLabel(dm, "top"));
62: PetscCall(DMCreateLabel(dm, "bottom"));
63: PetscCall(DMGetLabel(dm, "top", &top));
64: PetscCall(DMGetLabel(dm, "bottom", &bottom));
65: PetscCall(DMGetCoordinatesLocalSetUp(dm));
66: PetscCall(DMGetBoundingBox(dm, low, high));
67: midy = 0.5 * (high[1] - low[1]);
68: PetscCall(DMPlexGetHeightStratum(dm, 0, &cStart, &cEnd));
69: for (c = cStart; c < cEnd; ++c) {
70: PetscReal centroid[3];
72: PetscCall(DMPlexComputeCellGeometryFVM(dm, c, NULL, centroid, NULL));
73: if (centroid[1] > midy) PetscCall(DMLabelSetValue(top, c, 1));
74: else PetscCall(DMLabelSetValue(bottom, c, 1));
75: }
76: PetscCall(DMPlexLabelComplete(dm, top));
77: PetscFunctionReturn(PETSC_SUCCESS);
78: }
80: static PetscErrorCode CreateMesh(MPI_Comm comm, AppCtx *user, DM *dm)
81: {
82: PetscFunctionBeginUser;
83: PetscCall(DMCreate(comm, dm));
84: PetscCall(DMSetType(*dm, DMPLEX));
85: PetscCall(DMSetFromOptions(*dm));
86: PetscCall(DivideDomain(*dm, user));
87: PetscCall(DMSetApplicationContext(*dm, user));
88: PetscCall(DMViewFromOptions(*dm, NULL, "-dm_view"));
89: PetscFunctionReturn(PETSC_SUCCESS);
90: }
92: static PetscErrorCode SetupPrimalProblem(DM dm, AppCtx *user)
93: {
94: PetscDS ds;
95: PetscWeakForm wf;
96: DMLabel label;
97: const PetscInt id = 1;
99: PetscFunctionBeginUser;
100: PetscCall(DMGetRegionNumDS(dm, 0, &label, NULL, &ds, NULL));
101: PetscCall(PetscDSGetWeakForm(ds, &wf));
102: PetscCall(PetscWeakFormSetIndexResidual(wf, label, 1, 0, 0, 0, f0_quad_u, 0, f1_u));
103: PetscCall(PetscWeakFormSetIndexJacobian(wf, label, 1, 0, 0, 0, 0, NULL, 0, NULL, 0, NULL, 0, g3_uu));
104: PetscCall(PetscDSSetExactSolution(ds, 0, quad_u, user));
105: PetscCall(DMGetRegionNumDS(dm, 1, &label, NULL, &ds, NULL));
106: PetscCall(PetscDSGetWeakForm(ds, &wf));
107: PetscCall(PetscWeakFormSetIndexResidual(wf, label, 1, 0, 0, 0, f0_quad_u, 0, f1_u));
108: PetscCall(PetscWeakFormSetIndexJacobian(wf, label, 1, 0, 0, 0, 0, NULL, 0, NULL, 0, NULL, 0, g3_uu));
109: PetscCall(PetscWeakFormSetIndexResidual(wf, label, 1, 1, 0, 0, f0_quad_p, 0, NULL));
110: PetscCall(PetscWeakFormSetIndexJacobian(wf, label, 1, 1, 1, 0, 0, g0_pp, 0, NULL, 0, NULL, 0, NULL));
111: PetscCall(PetscDSSetExactSolution(ds, 0, quad_u, user));
112: PetscCall(PetscDSSetExactSolution(ds, 1, quad_p, user));
113: PetscCall(DMGetLabel(dm, "marker", &label));
114: PetscCall(DMAddBoundary(dm, DM_BC_ESSENTIAL, "wall", label, 1, &id, 0, 0, NULL, (void (*)(void))quad_u, NULL, user, NULL));
115: PetscFunctionReturn(PETSC_SUCCESS);
116: }
118: static PetscErrorCode SetupDiscretization(DM dm, const char name[], PetscErrorCode (*setup)(DM, AppCtx *), AppCtx *user)
119: {
120: DM cdm = dm;
121: DMLabel top;
122: PetscFE fe, feTop;
123: PetscQuadrature q;
124: PetscInt dim;
125: PetscBool simplex;
126: const char *nameTop = "pressure";
127: char prefix[PETSC_MAX_PATH_LEN];
129: PetscFunctionBeginUser;
130: PetscCall(DMGetDimension(dm, &dim));
131: PetscCall(DMPlexIsSimplex(dm, &simplex));
132: PetscCall(PetscSNPrintf(prefix, PETSC_MAX_PATH_LEN, "%s_", name));
133: PetscCall(PetscFECreateDefault(PetscObjectComm((PetscObject)dm), dim, 1, simplex, name ? prefix : NULL, -1, &fe));
134: PetscCall(PetscObjectSetName((PetscObject)fe, name));
135: PetscCall(DMSetField(dm, 0, NULL, (PetscObject)fe));
136: PetscCall(PetscFEGetQuadrature(fe, &q));
137: PetscCall(PetscFEDestroy(&fe));
138: PetscCall(DMGetLabel(dm, "top", &top));
139: PetscCall(PetscSNPrintf(prefix, PETSC_MAX_PATH_LEN, "%s_top_", nameTop));
140: PetscCall(PetscFECreateDefault(PetscObjectComm((PetscObject)dm), dim, 1, simplex, name ? prefix : NULL, -1, &feTop));
141: PetscCall(PetscObjectSetName((PetscObject)feTop, nameTop));
142: PetscCall(PetscFESetQuadrature(feTop, q));
143: PetscCall(DMSetField(dm, 1, top, (PetscObject)feTop));
144: PetscCall(PetscFEDestroy(&feTop));
145: PetscCall(DMCreateDS(dm));
146: PetscCall((*setup)(dm, user));
147: while (cdm) {
148: PetscCall(DMCopyDisc(dm, cdm));
149: PetscCall(DMGetCoarseDM(cdm, &cdm));
150: }
151: PetscFunctionReturn(PETSC_SUCCESS);
152: }
154: int main(int argc, char **argv)
155: {
156: DM dm; /* Problem specification */
157: SNES snes; /* Nonlinear solver */
158: Vec u; /* Solutions */
159: AppCtx user; /* User-defined work context */
161: PetscFunctionBeginUser;
162: PetscCall(PetscInitialize(&argc, &argv, NULL, help));
163: /* Primal system */
164: PetscCall(SNESCreate(PETSC_COMM_WORLD, &snes));
165: PetscCall(CreateMesh(PETSC_COMM_WORLD, &user, &dm));
166: PetscCall(SNESSetDM(snes, dm));
167: PetscCall(SetupDiscretization(dm, "potential", SetupPrimalProblem, &user));
168: PetscCall(DMCreateGlobalVector(dm, &u));
169: PetscCall(VecSet(u, 0.0));
170: PetscCall(PetscObjectSetName((PetscObject)u, "solution"));
171: PetscCall(DMPlexSetSNESLocalFEM(dm, PETSC_FALSE, &user));
172: PetscCall(SNESSetFromOptions(snes));
173: PetscCall(DMSNESCheckFromOptions(snes, u));
174: PetscCall(SNESSolve(snes, NULL, u));
175: PetscCall(SNESGetSolution(snes, &u));
176: PetscCall(VecViewFromOptions(u, NULL, "-sol_view"));
177: /* Cleanup */
178: PetscCall(VecDestroy(&u));
179: PetscCall(SNESDestroy(&snes));
180: PetscCall(DMDestroy(&dm));
181: PetscCall(PetscFinalize());
182: return 0;
183: }
185: /*TEST
187: test:
188: suffix: 2d_p1_0
189: requires: triangle
190: args: -potential_petscspace_degree 2 -pressure_top_petscspace_degree 0 -dm_refine 0 -dmsnes_check
192: test:
193: suffix: 2d_p1_1
194: requires: triangle
195: args: -potential_petscspace_degree 1 -pressure_top_petscspace_degree 0 -dm_refine 0 -convest_num_refine 3 -snes_convergence_estimate
197: TEST*/