MFEM  v4.5.2
Finite element discretization library
pmortarassembler.hpp
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11 
12 #ifndef MFEM_L2P_PAR_MORTAR_ASSEMBLER_HPP
13 #define MFEM_L2P_PAR_MORTAR_ASSEMBLER_HPP
14 
15 #include "../../config/config.hpp"
16 
17 #ifdef MFEM_USE_MPI
18 
19 #include <memory>
20 #include <vector>
21 
22 #include "../fem.hpp"
23 #include "mortarintegrator.hpp"
24 
25 namespace mfem
26 {
27 
28 /*!
29  * @brief This class implements the parallel variational transfer between finite
30  * element spaces. Variational transfer has been shown to have better
31  * approximation properties than standard interpolation. This facilities can be
32  * used for supporting applications which require the handling of non matching
33  * meshes. For instance: General multi-physics problems, fluid structure
34  * interaction, or even visualization of average quantities within subvolumes. This
35  * particular code is also used with LLNL for large scale multilevel Monte Carlo
36  * simulations.
37  * This algorithm allows to perform quadrature in the intersection of elements
38  * of two separate, unrelated, and arbitrarily distributed meshes.
39  * It generates quadrature rules in the intersection which allows us to
40  * integrate with to machine precision using the mfem::MortarIntegrator
41  * interface. See https://doi.org/10.1137/15M1008361 for and in-depth
42  * explanation. At this time curved elements are not supported.
43  * Convex non-affine elements are partially supported, however, high order (>3)
44  * finite element discretizations or nonlinear geometric transformations might
45  * generate undesired oscillations. Discontinuous fields in general can only
46  * be mapped to order 0 destination fields.
47  * For such cases localized versions of the projection will have to be developed.
48  */
50 {
51 public:
52  /*!
53  * @brief constructs the object with source and destination spaces
54  * @param source the source space from where we want to transfer the discrete
55  * field
56  * @param destination the source space to where we want to transfer the
57  * discrete field
58  */
59  ParMortarAssembler(const std::shared_ptr<ParFiniteElementSpace> &source,
60  const std::shared_ptr<ParFiniteElementSpace> &destination);
61 
63 
64  /*!
65  * @brief assembles the coupling matrix B. B : source -> destination If u is a
66  * coefficient associated with source and v with destination Then v = M^(-1) *
67  * B * u; where M is the mass matrix in destination. Works with
68  * L2_FECollection, H1_FECollection and DG_FECollection (experimental with
69  * RT_FECollection and ND_FECollection).
70  * @param B the assembled coupling operator. B can be passed uninitialized.
71  * @return true if there was an intersection and the operator has been
72  * assembled. False otherwise.
73  */
74  bool Assemble(std::shared_ptr<HypreParMatrix> &B);
75 
76  /*!
77  * @brief transfer a function from source to destination. if the transfer is
78  * to be performed multiple times use Assemble or Update/Apply instead
79  * @param src_fun the function associated with the source finite element space
80  * @param[out] dest_fun the function associated with the destination finite
81  * element space
82  * @return true if there was an intersection and the output can be used.
83  */
84  bool Transfer(const ParGridFunction &src_fun, ParGridFunction &dest_fun);
85 
86  /*!
87  * @brief transfer a function from source to destination. It requires that
88  * the Update function is called before
89  * @param src_fun the function associated with the source finite element space
90  * @param[out] dest_fun the function associated with the destination finite element space
91  * @return true if the transfer was successful, fail otherwise.
92  */
93  bool Apply(const ParGridFunction &src_fun, ParGridFunction &dest_fun);
94 
95  /*!
96  * @brief assembles the various components necessary for the transfer.
97  * To be called before calling the Apply function if the mesh geometry
98  * changed, after previous call. Works with L2_FECollection, H1_FECollection
99  * and DG_FECollection (experimental with RT_FECollection and
100  * ND_FECollection).
101  * @return true if there was an intersection and the operator has been
102  * assembled. False otherwise.
103  */
104  bool Update();
105 
106  /*!
107  * @brief This method must be called before Assemble or Transfer.
108  * It will assemble the operator in all intersections found.
109  * @param integrator the integrator object
110  */
111  void AddMortarIntegrator(const std::shared_ptr<MortarIntegrator> &integrator);
112 
113  /*!
114  * @brief Expose process details with verbose output
115  * @param verbose set to true for verbose output
116  */
117  void SetVerbose(const bool verbose);
118 
119 
120  /*!
121  * @brief Control if the Mass matrix is computed together with the coupling
122  * operator every time.
123  * @param value is set to true for computing the mass matrix operator with
124  * the coupling operator, false otherwise. The option is true by default,
125  * set to false if only the coupling operator is needed.
126  */
127  void SetAssembleMassAndCouplingTogether(const bool value);
128 
129 
130  /*!
131  * @brief Control the maximum numbers of conjugate gradients steps for mass
132  * matrix inversion
133  * @param max_solver_iterations the maximum number of iterations
134  */
135  void SetMaxSolverIterations(const int max_solver_iterations);
136 
137  /*!
138  * @brief Changes the solver to be used for solving the mass-matrix linear
139  * system
140  * @param solver new strategy
141  */
142  void SetSolver(const std::shared_ptr<IterativeSolver> &solver);
143 
144 
145  struct Impl;
146 
147  private:
148  std::unique_ptr<Impl> impl_;
149 };
150 
151 } // namespace mfem
152 
153 #endif // MFEM_USE_MPI
154 #endif // MFEM_L2P_PAR_MORTAR_ASSEMBLER_HPP
void SetVerbose(const bool verbose)
Expose process details with verbose output.
bool Apply(const ParGridFunction &src_fun, ParGridFunction &dest_fun)
transfer a function from source to destination. It requires that the Update function is called before...
This class implements the parallel variational transfer between finite element spaces. Variational transfer has been shown to have better approximation properties than standard interpolation. This facilities can be used for supporting applications which require the handling of non matching meshes. For instance: General multi-physics problems, fluid structure interaction, or even visualization of average quantities within subvolumes. This particular code is also used with LLNL for large scale multilevel Monte Carlo simulations. This algorithm allows to perform quadrature in the intersection of elements of two separate, unrelated, and arbitrarily distributed meshes. It generates quadrature rules in the intersection which allows us to integrate with to machine precision using the mfem::MortarIntegrator interface. See https://doi.org/10.1137/15M1008361 for and in-depth explanation. At this time curved elements are not supported. Convex non-affine elements are partially supported, however, high order (>3) finite element discretizations or nonlinear geometric transformations might generate undesired oscillations. Discontinuous fields in general can only be mapped to order 0 destination fields. For such cases localized versions of the projection will have to be developed.
bool Transfer(const ParGridFunction &src_fun, ParGridFunction &dest_fun)
transfer a function from source to destination. if the transfer is to be performed multiple times use...
void AddMortarIntegrator(const std::shared_ptr< MortarIntegrator > &integrator)
This method must be called before Assemble or Transfer. It will assemble the operator in all intersec...
void source(const Vector &x, Vector &f)
Definition: ex25.cpp:620
ParMortarAssembler(const std::shared_ptr< ParFiniteElementSpace > &source, const std::shared_ptr< ParFiniteElementSpace > &destination)
constructs the object with source and destination spaces
void SetMaxSolverIterations(const int max_solver_iterations)
Control the maximum numbers of conjugate gradients steps for mass matrix inversion.
bool Assemble(std::shared_ptr< HypreParMatrix > &B)
assembles the coupling matrix B. B : source -> destination If u is a coefficient associated with sour...
void SetAssembleMassAndCouplingTogether(const bool value)
Control if the Mass matrix is computed together with the coupling operator every time.
void SetSolver(const std::shared_ptr< IterativeSolver > &solver)
Changes the solver to be used for solving the mass-matrix linear system.
Class for parallel grid function.
Definition: pgridfunc.hpp:32
bool Update()
assembles the various components necessary for the transfer. To be called before calling the Apply fu...