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             : #include "libmesh/libmesh_logging.h"
      34             : 
      35             : // C++ includes
      36             : #include <time.h> // for clock_t, clock()
      37             : #include <cstdlib> // *must* precede <cmath> for proper std:abs() on PGI, Sun Studio CC
      38             : #include <cmath>
      39             : #include <iomanip>
      40             : #include <limits>
      41             : 
      42             : namespace libMesh
      43             : {
      44             : 
      45             : // Optimization at -O2 or greater seem to break Intel's icc. So if we are
      46             : // being compiled with icc let's dumb-down the optimizations for this file
      47             : #ifdef __INTEL_COMPILER
      48             : #  pragma optimize ( "", off )
      49             : #endif
      50             : 
      51             : // Member functions for the Variational Smoother
      52        2556 : VariationalMeshSmoother::VariationalMeshSmoother(
      53             :     UnstructuredMesh &mesh, Real dilation_weight,
      54             :     const bool preserve_subdomain_boundaries,
      55             :     const Real relative_residual_tolerance,
      56        2556 :     const Real absolute_residual_tolerance, const unsigned int verbosity)
      57        2412 :     : MeshSmoother(mesh), _verbosity(verbosity),
      58        2412 :       _dilation_weight(dilation_weight),
      59        2412 :       _preserve_subdomain_boundaries(preserve_subdomain_boundaries),
      60        2412 :       _setup_called(false),
      61        2412 :       _relative_residual_tolerance(relative_residual_tolerance),
      62        2628 :       _absolute_residual_tolerance(absolute_residual_tolerance) {}
      63             : 
      64        2556 : void VariationalMeshSmoother::setup()
      65             : {
      66             :   // Check for multiple dimensions
      67        2628 :   if (!_mesh.preparation().has_cached_elem_data)
      68         923 :     _mesh.cache_elem_data();
      69             : 
      70        2628 :   if (_mesh.elem_dimensions().size() > 1)
      71           0 :     libmesh_not_implemented_msg("Meshes containing elements of differing dimension are not yet supported.");
      72             : 
      73             :   /*
      74             :   Ideally we'd want to update _mesh directly even if it already has an
      75             :   EquationSystems attached and doing work on it ... and that's thwarted by the
      76             :   problems:
      77             : 
      78             :   1. We can't easily tell if there's already an EquationSystems attached.
      79             :   2. We can't attach a second EquationSystems safely (if it already has a system 0)
      80             :      because the DoF indexing will need to be overwritten by our system.
      81             :   3. The destructor of es won't even clean up after itself (we generally expect
      82             :      a mesh to go unused after its EquationSystems is destroyed), much less know
      83             :      how to restore anything from a previous EquationSystems.
      84             : 
      85             :   To avoid these issues, we'll just construct a new DistributedMesh _mesh_copy
      86             :   from _mesh, then do the solve on _mesh_copy, then copy its node locations back
      87             :   to _mesh after the solve is done. That'll be slightly less memory-efficient
      88             :   and somewhat more CPU-efficient in the case where _mesh is serial, though
      89             :   it'll be significantly less memory-efficient when _mesh is already distributed,
      90             :   but either way the robustness is probably worth it.
      91             :   */
      92             : 
      93             :   // Create a new mesh, EquationSystems, and System
      94        5040 :   _mesh_copy = std::make_unique<DistributedMesh>(_mesh);
      95             : 
      96             :   // If the _mesh wasn't prepared, that's fine (we'll just be moving
      97             :   // its nodes), but we do need the copy to be prepared before our
      98             :   // solve does things like looking at neighbors.  We'll disable
      99             :   // repartitioning and renumbering first to make sure that we can
     100             :   // transfer our geometry changes back to the original mesh.
     101          72 :   _mesh_copy->allow_renumbering(false);
     102          72 :   _mesh_copy->skip_partitioning(true);
     103        2556 :   _mesh_copy->complete_preparation();
     104             : 
     105        5040 :   _equation_systems = std::make_unique<EquationSystems>(*_mesh_copy);
     106        2556 :   _system =
     107        2556 :       &(_equation_systems->add_system<VariationalSmootherSystem>("variational_smoother_system"));
     108             : 
     109             :   // Set this to something > 0 to add more quadrature points than the default
     110             :   // rule that integrates order 2 * fe_order + 1 polynomials exactly.
     111             :   // Using higher quadrature orders has not had a significant effect on observed solutions.
     112             :   //system()->extra_quadrature_order = 0;
     113             : 
     114             :   // The default Gauss rule samples the element interior only, so it can miss
     115             :   // degeneracies localized at element corners (e.g. an element collapsing
     116             :   // toward one of its nodes). Selecting a vertex-sampling rule (QTRAP,
     117             :   // QSIMPSON, QNODAL, QGAUSS_LOBATTO) evaluates the metric at the element
     118             :   // nodes instead. Defaults to QGAUSS.
     119        2556 :   system()->set_quadrature_type(_quadrature_type);
     120             : 
     121             :   // Uncomment these to debug
     122             :   //system()->print_element_solutions=true;
     123             :   //system()->print_element_residuals=true;
     124             :   //system()->print_element_jacobians=true;
     125             : 
     126             :   // Add boundary node and hanging node constraints
     127        4968 :   _constraint = std::make_unique<VariationalSmootherConstraint>(
     128          72 :       *_system, _preserve_subdomain_boundaries, _verbosity);
     129        2628 :   system()->attach_constraint_object(*_constraint);
     130             : 
     131             :   // Set system parameters
     132        2556 :   system()->set_verbosity(_verbosity);
     133        2556 :   system()->get_dilation_weight() = _dilation_weight;
     134             : 
     135             :   // Set up solver
     136        2628 :   system()->time_solver = std::make_unique<SteadySolver>(*_system);
     137             : 
     138             :   // Uncomment this line and use -snes_test_jacobian and -snes_test_jacobian_view
     139             :   // flags to compare the hand-coded jacobian in VariationalSmootherSystem
     140             :   // to finite difference jacobians.
     141             :   //system()->time_solver->diff_solver() = std::make_unique<PetscDiffSolver>(*_system);
     142             : 
     143        2556 :   _equation_systems->init();
     144             : 
     145             :   // Solver verbosity
     146        2556 :   if (_verbosity > 15) {
     147         146 :     DiffSolver &solver = *(system()->time_solver->diff_solver().get());
     148         142 :     solver.quiet = false;
     149         142 :     solver.verbose = true;
     150             :   }
     151             : 
     152             :   // Solver convergence tolerances
     153        2628 :   system()->time_solver->diff_solver()->relative_residual_tolerance = _relative_residual_tolerance;
     154        2628 :   system()->time_solver->diff_solver()->absolute_residual_tolerance = _absolute_residual_tolerance;
     155             : 
     156        2556 :   _setup_called = true;
     157        2556 : }
     158             : 
     159        2556 : void VariationalMeshSmoother::smooth()
     160             : {
     161          72 :   LOG_SCOPE("smooth()", "VariationalMeshSmoother");
     162             : 
     163        2556 :   if (!_setup_called)
     164        2414 :     setup();
     165             : 
     166             :   libmesh_try
     167             :     {
     168        2556 :       system()->solve();
     169             :     }
     170             : 
     171           0 :   libmesh_catch (ConvergenceFailure& e)
     172             :     {
     173             : #ifdef LIBMESH_ENABLE_EXCEPTIONS
     174           0 :       throw ConvergenceFailure("The VariationalMeshSmoother solve failed to converge.");
     175             : #endif
     176           0 :     }
     177             : 
     178             :   // Update _mesh from _mesh_copy
     179       77772 :   for (auto * node_copy : _mesh_copy->local_node_ptr_range())
     180             :     {
     181       39672 :       auto & node = _mesh.node_ref(node_copy->id());
     182      154332 :       for (const auto d : make_range(_mesh_copy->mesh_dimension()))
     183      114660 :         node(d) = (*node_copy)(d);
     184        2412 :     }
     185             : 
     186        2556 :   SyncNodalPositions sync_object(_mesh);
     187        5040 :   Parallel::sync_dofobject_data_by_id (_mesh.comm(), _mesh.nodes_begin(), _mesh.nodes_end(), sync_object);
     188             : 
     189             :   // Release memory occupied by _mesh_copy
     190             :   // Destruct this before _mesh_copy because it references _mesh_copy
     191          72 :   _equation_systems.reset();
     192          72 :   _mesh_copy.reset();
     193             :   // We'll need to call setup again since we'll have to reconstruct _mesh_copy
     194        2556 :   _setup_called = false;
     195        2556 : }
     196             : 
     197         142 : const MeshQualityInfo & VariationalMeshSmoother::get_mesh_info() const
     198             : {
     199         142 :   libmesh_error_msg_if(!_setup_called, "Need to first call the setup() method of "
     200             :       << "this VariationalMeshSmoother object, then call get_mesh_info() prior "
     201             :       << "to calling smooth().");
     202         142 :   return _system->get_mesh_info();
     203             : }
     204             : 
     205             : } // namespace libMesh
     206             : 
     207             : #endif // defined(LIBMESH_ENABLE_VSMOOTHER)