MFEM  v4.5.2 Finite element discretization library
ex1p.cpp
Go to the documentation of this file.
1 // MFEM Example 1 - Parallel Version
2 // PUMI Modification
3 //
4 // Compile with: make ex1p
5 //
6 // Sample runs:
7 // mpirun -np 8 ex1p -m ../../data/pumi/parallel/Kova/Kova100k_8.smb
8 // -p ../../data/pumi/geom/Kova.dmg -o 1 -go 2
9 //
10 // Note: Example models + meshes for the PUMI examples can be downloaded
12 // creating a symbolic link to the above directory in ../../data.
13 //
14 // Description: This example code demonstrates the use of MFEM to define a
15 // simple finite element discretization of the Laplace problem
16 // -Delta u = 1 with homogeneous Dirichlet boundary conditions.
17 // Specifically, we discretize using a FE space of the specified
18 // order, or if order < 1 using an isoparametric/isogeometric
20 // NURBS mesh, etc.)
21 //
22 // The example highlights the use of mesh refinement, finite
23 // element grid functions, as well as linear and bilinear forms
24 // corresponding to the left-hand side and right-hand side of the
25 // discrete linear system. We also cover the explicit elimination
26 // of essential boundary conditions, static condensation, and the
27 // optional connection to the GLVis tool for visualization.
28 //
29 // This PUMI modification demonstrates how PUMI's API can be used
30 // to load a parallel PUMI mesh classified on a geometric model
31 // and then generate the corresponding parallel MFEM mesh. The
32 // example also performs a "uniform" refinement, similar to the
33 // MFEM examples, for coarse meshes. However, the refinement is
34 // performed using the PUMI API. The inputs are a Parasolid
35 // model, "*.xmt_txt" and SCOREC parallel meshes "*.smb". The
36 // option "-o" is used for the Finite Element order and "-go" for
37 // the geometry order. Note that they can be used independently:
38 // "-o 8 -go 3" solves for 8th order FE on third order geometry.
39 //
40 // NOTE: Model/Mesh files for this example are in the (large) data file
41 // repository of MFEM here https://github.com/mfem/data under the
42 // folder named "pumi", which consists of the following sub-folders:
43 // a) geom --> model files
44 // b) parallel --> parallel pumi mesh files
45 // c) serial --> serial pumi mesh files
46
47
48 #include "mfem.hpp"
49 #include <fstream>
50 #include <iostream>
51
52 #ifdef MFEM_USE_SIMMETRIX
53 #include <SimUtil.h>
54 #include <gmi_sim.h>
55 #endif
56 #include <apfMDS.h>
57 #include <gmi_null.h>
58 #include <PCU.h>
59 #include <apfConvert.h>
60 #include <gmi_mesh.h>
61 #include <crv.h>
62
63 #ifndef MFEM_USE_PUMI
64 #error This example requires that MFEM is built with MFEM_USE_PUMI=YES
65 #endif
66
67 using namespace std;
68 using namespace mfem;
69
70 int main(int argc, char *argv[])
71 {
72  // 1. Initialize MPI and HYPRE.
73  Mpi::Init(argc, argv);
74  int num_procs = Mpi::WorldSize();
75  int myid = Mpi::WorldRank();
76  Hypre::Init();
77
78  // 2. Parse command-line options.
79  const char *mesh_file = "../../data/pumi/parallel/Kova/Kova100k_8.smb";
80 #ifdef MFEM_USE_SIMMETRIX
81  const char *model_file = "../../data/pumi/geom/Kova.x_t";
82 #else
83  const char *model_file = "../../data/pumi/geom/Kova.dmg";
84 #endif
85  int order = 1;
86  bool static_cond = false;
87  bool visualization = 1;
88  int geom_order = 1;
89
90  OptionsParser args(argc, argv);
92  "Mesh file to use.");
94  "Finite element order (polynomial degree) or -1 for"
95  " isoparametric space.");
97  "--no-static-condensation", "Enable static condensation.");
99  "--no-visualization",
100  "Enable or disable GLVis visualization.");
102  "Parasolid model to use.");
104  "Geometric order of the model");
105  args.Parse();
106  if (!args.Good())
107  {
108  if (myid == 0)
109  {
110  args.PrintUsage(cout);
111  }
112  return 1;
113  }
114  if (myid == 0)
115  {
116  args.PrintOptions(cout);
117  }
118
119  // 3. Read the SCOREC Mesh
120  PCU_Comm_Init();
121 #ifdef MFEM_USE_SIMMETRIX
123  gmi_sim_start();
124  gmi_register_sim();
125 #endif
126  gmi_register_mesh();
127
128  apf::Mesh2* pumi_mesh;
130
131  // 4. Increase the geometry order and refine the mesh if necessary. Parallel
132  // uniform refinement is performed if the total number of elements is less
133  // than 10,000.
134  int dim = pumi_mesh->getDimension();
135  int nEle = pumi_mesh->count(dim);
136  int ref_levels = (int)floor(log(10000./nEle)/log(2.)/dim);
137
138  if (geom_order > 1)
139  {
140  crv::BezierCurver bc(pumi_mesh, geom_order, 2);
141  bc.run();
142  }
143
144  // Perform Uniform refinement
145  if (ref_levels > 1)
146  {
147  auto uniInput = ma::configureUniformRefine(pumi_mesh, ref_levels);
148
149  if (geom_order > 1)
150  {
152  }
153  else
154  {
156  }
157  }
158
159  pumi_mesh->verify();
160
161  // 5. Create the parallel MFEM mesh object from the parallel PUMI mesh.
162  // We can handle triangular and tetrahedral meshes. Note that the
163  // mesh resolution is performed on the PUMI mesh.
164  ParMesh *pmesh = new ParPumiMesh(MPI_COMM_WORLD, pumi_mesh);
165
166  // 6. Define a parallel finite element space on the parallel mesh. Here we
167  // use continuous Lagrange finite elements of the specified order. If
168  // order < 1, we instead use an isoparametric/isogeometric space.
170  if (order > 0)
171  {
172  fec = new H1_FECollection(order, dim);
173  }
174  else if (pmesh->GetNodes())
175  {
176  fec = pmesh->GetNodes()->OwnFEC();
177  if (myid == 0)
178  {
179  cout << "Using isoparametric FEs: " << fec->Name() << endl;
180  }
181  }
182  else
183  {
184  fec = new H1_FECollection(order = 1, dim);
185  }
186  ParFiniteElementSpace *fespace = new ParFiniteElementSpace(pmesh, fec);
187  HYPRE_BigInt size = fespace->GlobalTrueVSize();
188  if (myid == 0)
189  {
190  cout << "Number of finite element unknowns: " << size << endl;
191  }
192
193  // 7. Determine the list of true (i.e. parallel conforming) essential
194  // boundary dofs. In this example, the boundary conditions are defined
195  // by marking all the boundary attributes from the mesh as essential
196  // (Dirichlet) and converting them to a list of true dofs.
197  Array<int> ess_tdof_list;
198  if (pmesh->bdr_attributes.Size())
199  {
200  Array<int> ess_bdr(pmesh->bdr_attributes.Max());
201  ess_bdr = 1;
202  fespace->GetEssentialTrueDofs(ess_bdr, ess_tdof_list);
203  }
204
205  // 8. Set up the parallel linear form b(.) which corresponds to the
206  // right-hand side of the FEM linear system, which in this case is
207  // (1,phi_i) where phi_i are the basis functions in fespace.
208  ParLinearForm *b = new ParLinearForm(fespace);
209  ConstantCoefficient one(1.0);
211  b->Assemble();
212
213  // 9. Define the solution vector x as a parallel finite element grid function
214  // corresponding to fespace. Initialize x with initial guess of zero,
215  // which satisfies the boundary conditions.
216  ParGridFunction x(fespace);
217  x = 0.0;
218
219  // 10. Set up the parallel bilinear form a(.,.) on the finite element space
220  // corresponding to the Laplacian operator -Delta, by adding the Diffusion
221  // domain integrator.
222  ParBilinearForm *a = new ParBilinearForm(fespace);
224
225  // 11. Assemble the parallel bilinear form and the corresponding linear
226  // system, applying any necessary transformations such as: parallel
227  // assembly, eliminating boundary conditions, applying conforming
228  // constraints for non-conforming AMR, static condensation, etc.
229  if (static_cond) { a->EnableStaticCondensation(); }
230  a->Assemble();
231
232  HypreParMatrix A;
233  Vector B, X;
234  a->FormLinearSystem(ess_tdof_list, x, *b, A, X, B);
235
236  if (myid == 0)
237  {
238  cout << "Size of linear system: " << A.GetGlobalNumRows() << endl;
239  }
240
241  // 12. Define and apply a parallel PCG solver for AX=B with the BoomerAMG
242  // preconditioner from hypre.
243  HypreSolver *amg = new HypreBoomerAMG(A);
244  HyprePCG *pcg = new HyprePCG(A);
245  pcg->SetTol(1e-12);
246  pcg->SetMaxIter(200);
247  pcg->SetPrintLevel(2);
248  pcg->SetPreconditioner(*amg);
249  pcg->Mult(B, X);
250
251  // 13. Recover the parallel grid function corresponding to X. This is the
252  // local finite element solution on each processor.
253  a->RecoverFEMSolution(X, *b, x);
254
255  // 14. Save the refined mesh and the solution in parallel. This output can
256  // be viewed later using GLVis: "glvis -np <np> -m mesh -g sol".
257  {
258  ostringstream mesh_name, sol_name;
259  mesh_name << "mesh." << setfill('0') << setw(6) << myid;
260  sol_name << "sol." << setfill('0') << setw(6) << myid;
261
262  ofstream mesh_ofs(mesh_name.str().c_str());
263  mesh_ofs.precision(8);
264  pmesh->Print(mesh_ofs);
265
266  ofstream sol_ofs(sol_name.str().c_str());
267  sol_ofs.precision(8);
268  x.Save(sol_ofs);
269  }
270
271  // 15. Send the solution by socket to a GLVis server.
272  if (visualization)
273  {
274  char vishost[] = "localhost";
275  int visport = 19916;
276  socketstream sol_sock(vishost, visport);
277  sol_sock << "parallel " << num_procs << " " << myid << "\n";
278  sol_sock.precision(8);
279  sol_sock << "solution\n" << *pmesh << x << flush;
280  }
281
282  // 16. Free the used memory.
283  delete pcg;
284  delete amg;
285  delete a;
286  delete b;
287  delete fespace;
288  if (order > 0) { delete fec; }
289  delete pmesh;
290
291  pumi_mesh->destroyNative();
292  apf::destroyMesh(pumi_mesh);
293  PCU_Comm_Free();
294
295 #ifdef MFEM_USE_SIMMETRIX
296  gmi_sim_stop();
297  Sim_unregisterAllKeys();
298 #endif
299
300  return 0;
301 }
void SetTol(double tol)
Definition: hypre.cpp:3996
Class for domain integration L(v) := (f, v)
Definition: lininteg.hpp:108
virtual void GetEssentialTrueDofs(const Array< int > &bdr_attr_is_ess, Array< int > &ess_tdof_list, int component=-1)
Definition: pfespace.cpp:1032
A coefficient that is constant across space and time.
Definition: coefficient.hpp:84
void PrintOptions(std::ostream &out) const
Print the options.
Definition: optparser.cpp:324
void PrintUsage(std::ostream &out) const
Print the usage message.
Definition: optparser.cpp:454
virtual void Mult(const HypreParVector &b, HypreParVector &x) const
Solve Ax=b with hypre&#39;s PCG.
Definition: hypre.cpp:4044
T Max() const
Find the maximal element in the array, using the comparison operator < for class T.
Definition: array.cpp:68
bool Good() const
Return true if the command line options were parsed successfully.
Definition: optparser.hpp:150
Abstract parallel finite element space.
Definition: pfespace.hpp:28
STL namespace.
void SetPrintLevel(int print_lvl)
Definition: hypre.cpp:4016
Class for PUMI parallel meshes.
Definition: pumi.hpp:69
The BoomerAMG solver in hypre.
Definition: hypre.hpp:1590
Class for parallel linear form.
Definition: plinearform.hpp:26
void Parse()
Parse the command-line options. Note that this function expects all the options provided through the ...
Definition: optparser.cpp:151
constexpr char vishost[]
double b
Definition: lissajous.cpp:42
constexpr int visport
virtual const char * Name() const
Definition: fe_coll.hpp:73
HYPRE_BigInt GlobalTrueVSize() const
Definition: pfespace.hpp:285
void SetMaxIter(int max_iter)
Definition: hypre.cpp:4006
Array< int > bdr_attributes
A list of all unique boundary attributes used by the Mesh.
Definition: mesh.hpp:275
PCG solver in hypre.
Definition: hypre.hpp:1215
Collection of finite elements from the same family in multiple dimensions. This class is used to matc...
Definition: fe_coll.hpp:26
void AddOption(bool *var, const char *enable_short_name, const char *enable_long_name, const char *disable_short_name, const char *disable_long_name, const char *description, bool required=false)
Add a boolean option and set &#39;var&#39; to receive the value. Enable/disable tags are used to set the bool...
Definition: optparser.hpp:82
HYPRE_Int HYPRE_BigInt
int main(int argc, char *argv[])
Definition: ex1p.cpp:69
virtual void Save(std::ostream &out) const
Definition: pgridfunc.cpp:873
double a
Definition: lissajous.cpp:41
int dim
Definition: ex24.cpp:53
void SetPreconditioner(HypreSolver &precond)
Set the hypre solver to be used as a preconditioner.
Definition: hypre.cpp:4021
Class for parallel bilinear form.
Abstract class for hypre&#39;s solvers and preconditioners.
Definition: hypre.hpp:1102
int Size() const
Return the logical size of the array.
Definition: array.hpp:141
Vector data type.
Definition: vector.hpp:60
Arbitrary order H1-conforming (continuous) finite elements.
Definition: fe_coll.hpp:252
void GetNodes(Vector &node_coord) const
Definition: mesh.cpp:7949
void Print(std::ostream &out=mfem::out) const override
Definition: pmesh.cpp:4839
Class for parallel grid function.
Definition: pgridfunc.hpp:32
Wrapper for hypre&#39;s ParCSR matrix class.
Definition: hypre.hpp:343
Class for parallel meshes.
Definition: pmesh.hpp:32
HYPRE_BigInt GetGlobalNumRows() const
Return the global number of rows.
Definition: hypre.hpp:635