Line data    Source code

       1             : // The libMesh Finite Element Library.
       2             : // Copyright (C) 2002-2026 Benjamin S. Kirk, John W. Peterson, Roy H. Stogner
       3             : 
       4             : // This library is free software; you can redistribute it and/or
       5             : // modify it under the terms of the GNU Lesser General Public
       6             : // License as published by the Free Software Foundation; either
       7             : // version 2.1 of the License, or (at your option) any later version.
       8             : 
       9             : // This library is distributed in the hope that it will be useful,
      10             : // but WITHOUT ANY WARRANTY; without even the implied warranty of
      11             : // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
      12             : // Lesser General Public License for more details.
      13             : 
      14             : // You should have received a copy of the GNU Lesser General Public
      15             : // License along with this library; if not, write to the Free Software
      16             : // Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
      17             : 
      18             : #include "libmesh/libmesh_config.h"
      19             : #if defined(LIBMESH_ENABLE_VSMOOTHER)
      20             : 
      21             : // Local includes
      22             : #include "libmesh/mesh_smoother_vsmoother.h"
      23             : #include "libmesh/mesh_tools.h"
      24             : #include "libmesh/elem.h"
      25             : #include "libmesh/unstructured_mesh.h"
      26             : #include "libmesh/utility.h"
      27             : #include "libmesh/boundary_info.h"
      28             : #include "libmesh/equation_systems.h"
      29             : #include "libmesh/distributed_mesh.h"
      30             : #include "libmesh/steady_solver.h"
      31             : #include "libmesh/diff_solver.h"
      32             : #include "libmesh/parallel_ghost_sync.h"
      33             : 
      34             : // C++ includes
      35             : #include <time.h> // for clock_t, clock()
      36             : #include <cstdlib> // *must* precede <cmath> for proper std:abs() on PGI, Sun Studio CC
      37             : #include <cmath>
      38             : #include <iomanip>
      39             : #include <limits>
      40             : 
      41             : namespace libMesh
      42             : {
      43             : 
      44             : // Optimization at -O2 or greater seem to break Intel's icc. So if we are
      45             : // being compiled with icc let's dumb-down the optimizations for this file
      46             : #ifdef __INTEL_COMPILER
      47             : #  pragma optimize ( "", off )
      48             : #endif
      49             : 
      50             : // Member functions for the Variational Smoother
      51        2414 : VariationalMeshSmoother::VariationalMeshSmoother(
      52             :     UnstructuredMesh &mesh, Real dilation_weight,
      53             :     const bool preserve_subdomain_boundaries,
      54             :     const Real relative_residual_tolerance,
      55        2414 :     const Real absolute_residual_tolerance, const unsigned int verbosity)
      56        2278 :     : MeshSmoother(mesh), _verbosity(verbosity),
      57        2278 :       _dilation_weight(dilation_weight),
      58        2278 :       _preserve_subdomain_boundaries(preserve_subdomain_boundaries),
      59        2278 :       _setup_called(false),
      60        2278 :       _relative_residual_tolerance(relative_residual_tolerance),
      61        2482 :       _absolute_residual_tolerance(absolute_residual_tolerance) {}
      62             : 
      63        2414 : void VariationalMeshSmoother::setup()
      64             : {
      65             :   // Check for multiple dimensions
      66        2482 :   if (_mesh.elem_dimensions().size() > 1)
      67           0 :     libmesh_not_implemented_msg("Meshes containing elements of differing dimension are not yet supported.");
      68             : 
      69             :   /*
      70             :   Ideally we'd want to update _mesh directly even if it already has an
      71             :   EquationSystems attached and doing work on it ... and that's thwarted by the
      72             :   problems:
      73             : 
      74             :   1. We can't easily tell if there's already an EquationSystems attached.
      75             :   2. We can't attach a second EquationSystems safely (if it already has a system 0)
      76             :      because the DoF indexing will need to be overwritten by our system.
      77             :   3. The destructor of es won't even clean up after itself (we generally expect
      78             :      a mesh to go unused after its EquationSystems is destroyed), much less know
      79             :      how to restore anything from a previous EquationSystems.
      80             : 
      81             :   To avoid these issues, we'll just construct a new DistributedMesh _mesh_copy
      82             :   from _mesh, then do the solve on _mesh_copy, then copy its node locations back
      83             :   to _mesh after the solve is done. That'll be slightly less memory-efficient
      84             :   and somewhat more CPU-efficient in the case where _mesh is serial, though
      85             :   it'll be significantly less memory-efficient when _mesh is already distributed,
      86             :   but either way the robustness is probably worth it.
      87             :   */
      88             : 
      89             :   // Create a new mesh, EquationSystems, and System
      90        4760 :   _mesh_copy = std::make_unique<DistributedMesh>(_mesh);
      91             : 
      92             :   // If the _mesh wasn't prepared, that's fine (we'll just be moving
      93             :   // its nodes), but we do need the copy to be prepared before our
      94             :   // solve does things like looking at neighbors.  We'll disable
      95             :   // repartitioning and renumbering first to make sure that we can
      96             :   // transfer our geometry changes back to the original mesh.
      97          68 :   _mesh_copy->allow_renumbering(false);
      98          68 :   _mesh_copy->skip_partitioning(true);
      99        2414 :   _mesh_copy->complete_preparation();
     100             : 
     101        4760 :   _equation_systems = std::make_unique<EquationSystems>(*_mesh_copy);
     102        2414 :   _system =
     103        2414 :       &(_equation_systems->add_system<VariationalSmootherSystem>("variational_smoother_system"));
     104             : 
     105             :   // Set this to something > 0 to add more quadrature points than the default
     106             :   // rule that integrates order 2 * fe_order + 1 polynomials exactly.
     107             :   // Using higher quadrature orders has not had a significant effect on observed solutions.
     108             :   //system()->extra_quadrature_order = 0;
     109             : 
     110             :   // Uncomment these to debug
     111             :   //system()->print_element_solutions=true;
     112             :   //system()->print_element_residuals=true;
     113             :   //system()->print_element_jacobians=true;
     114             : 
     115             :   // Add boundary node and hanging node constraints
     116        2482 :   _constraint = std::make_unique<VariationalSmootherConstraint>(
     117        2414 :       *_system, _preserve_subdomain_boundaries, _verbosity);
     118        2482 :   system()->attach_constraint_object(*_constraint);
     119             : 
     120             :   // Set system parameters
     121        2414 :   system()->set_verbosity(_verbosity);
     122        2414 :   system()->get_dilation_weight() = _dilation_weight;
     123             : 
     124             :   // Set up solver
     125        2482 :   system()->time_solver = std::make_unique<SteadySolver>(*_system);
     126             : 
     127             :   // Uncomment this line and use -snes_test_jacobian and -snes_test_jacobian_view
     128             :   // flags to compare the hand-coded jacobian in VariationalSmootherSystem
     129             :   // to finite difference jacobians.
     130             :   //system()->time_solver->diff_solver() = std::make_unique<PetscDiffSolver>(*_system);
     131             : 
     132        2414 :   _equation_systems->init();
     133             : 
     134             :   // Solver verbosity
     135        2414 :   if (_verbosity > 15) {
     136         146 :     DiffSolver &solver = *(system()->time_solver->diff_solver().get());
     137         142 :     solver.quiet = false;
     138         142 :     solver.verbose = true;
     139             :   }
     140             : 
     141             :   // Solver convergence tolerances
     142        2482 :   system()->time_solver->diff_solver()->relative_residual_tolerance = _relative_residual_tolerance;
     143        2482 :   system()->time_solver->diff_solver()->absolute_residual_tolerance = _absolute_residual_tolerance;
     144             : 
     145        2414 :   _setup_called = true;
     146        2414 : }
     147             : 
     148        2414 : void VariationalMeshSmoother::smooth()
     149             : {
     150        2414 :   if (!_setup_called)
     151        2272 :     setup();
     152             : 
     153             :   libmesh_try
     154             :     {
     155        2414 :       system()->solve();
     156             :     }
     157             : 
     158           0 :   libmesh_catch (ConvergenceFailure& e)
     159             :     {
     160             : #ifdef LIBMESH_ENABLE_EXCEPTIONS
     161           0 :       throw ConvergenceFailure("The VariationalMeshSmoother solve failed to converge.");
     162             : #endif
     163           0 :     }
     164             : 
     165             :   // Update _mesh from _mesh_copy
     166       75952 :   for (auto * node_copy : _mesh_copy->local_node_ptr_range())
     167             :     {
     168       38832 :       auto & node = _mesh.node_ref(node_copy->id());
     169      151812 :       for (const auto d : make_range(_mesh_copy->mesh_dimension()))
     170      112980 :         node(d) = (*node_copy)(d);
     171        2278 :     }
     172             : 
     173        2414 :   SyncNodalPositions sync_object(_mesh);
     174        4760 :   Parallel::sync_dofobject_data_by_id (_mesh.comm(), _mesh.nodes_begin(), _mesh.nodes_end(), sync_object);
     175             : 
     176             :   // Release memory occupied by _mesh_copy
     177             :   // Destruct this before _mesh_copy because it references _mesh_copy
     178          68 :   _equation_systems.reset();
     179          68 :   _mesh_copy.reset();
     180             :   // We'll need to call setup again since we'll have to reconstruct _mesh_copy
     181        2414 :   _setup_called = false;
     182        2414 : }
     183             : 
     184         142 : const MeshQualityInfo & VariationalMeshSmoother::get_mesh_info() const
     185             : {
     186         142 :   libmesh_error_msg_if(!_setup_called, "Need to first call the setup() method of "
     187             :       << "this VariationalMeshSmoother object, then call get_mesh_info() prior "
     188             :       << "to calling smooth().");
     189         142 :   return _system->get_mesh_info();
     190             : }
     191             : 
     192             : } // namespace libMesh
     193             : 
     194             : #endif // defined(LIBMESH_ENABLE_VSMOOTHER)