RefineBlockGenerator.C

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//* This file is part of the MOOSE framework
//* https://mooseframework.inl.gov
//*
//* All rights reserved, see COPYRIGHT for full restrictions
//* https://github.com/idaholab/moose/blob/master/COPYRIGHT
//*
//* Licensed under LGPL 2.1, please see LICENSE for details
//* https://www.gnu.org/licenses/lgpl-2.1.html

#include "RefineBlockGenerator.h"
#include "MooseMeshUtils.h"

#include "libmesh/elem.h"
#include "libmesh/mesh_refinement.h"
#include "CastUniquePointer.h"

registerMooseObject("MooseApp", RefineBlockGenerator);

InputParameters
RefineBlockGenerator::validParams()
{
  InputParameters params = MeshGenerator::validParams();

  params.addClassDescription("Mesh generator which refines one or more blocks in an existing mesh");
  params.addRequiredParam<MeshGeneratorName>("input", "Input mesh to refine");
  params.addRequiredParam<std::vector<SubdomainName>>("block", "The list of blocks to be refined");
  params.addRequiredParam<std::vector<unsigned int>>(
      "refinement",
      "Minimum amount of times to refine each block, corresponding to their index in 'block'. A "
      "single value can be specified to refine all blocks.");
  params.addParam<bool>(
      "enable_neighbor_refinement",
      true,
      "Toggles whether neighboring level one elements should be refined or not. Defaults to true. "
      "False may lead to unsupported mesh non-conformality without great care.");
  params.addParam<Real>(
      "max_element_volume", 1e8, "If elements are above that size, they will be refined more");

  return params;
}

RefineBlockGenerator::RefineBlockGenerator(const InputParameters & parameters)
  : MeshGenerator(parameters),
    _input(getMesh("input")),
    _block(getParam<std::vector<SubdomainName>>("block")),
    _refinement(getParam<std::vector<unsigned int>>("refinement")),
    _enable_neighbor_refinement(getParam<bool>("enable_neighbor_refinement")),
    _max_element_volume(getParam<Real>("max_element_volume"))
{
  if (_refinement.size() == 1)
    _refinement.resize(_block.size(), _refinement[0]);
  if (_block.size() != _refinement.size())
    paramError("refinement", "The blocks and refinement parameter vectors should be the same size");
}

std::unique_ptr<MeshBase>
RefineBlockGenerator::generate()
{
  // Get the list of block ids from the block names
  const auto block_ids =
      MooseMeshUtils::getSubdomainIDs(*_input, getParam<std::vector<SubdomainName>>("block"));

  // Check that the block ids/names exist in the mesh
  if (!_input->preparation().has_cached_elem_data)
    _input->cache_elem_data();
  std::set<SubdomainID> mesh_blocks;
  _input->subdomain_ids(mesh_blocks);

  for (std::size_t i = 0; i < block_ids.size(); ++i)
    if (!MooseMeshUtils::hasSubdomainID(*_input, block_ids[i]))
      paramError("block",
                 "The block '",
                 getParam<std::vector<SubdomainName>>("block")[i],
                 "' was not found within the mesh.\nBlock ID: ",
                 block_ids[i],
                 "\nBlock IDs in the mesh: ",
                 Moose::stringify(mesh_blocks));

  std::unique_ptr<MeshBase> mesh = std::move(_input);
  int max = *std::max_element(_refinement.begin(), _refinement.end());

  if (max > 0 && !mesh->is_replicated() && !mesh->is_prepared())
    // refinement requires that (or at least it asserts that) the mesh is either replicated or
    // prepared
    mesh->prepare_for_use();

  auto mesh_ptr = recursive_refine(block_ids, mesh, _refinement, max);

  if (max > 0 && !mesh_ptr->is_replicated() && !mesh_ptr->is_prepared())
    // refinement requires that (or at least it asserts that) the mesh is either replicated or
    // prepared
    mesh_ptr->prepare_for_use();

  // Refine elements that are too big
  bool found_element_to_refine = true;
  bool refined_on_size = false;
  while (found_element_to_refine)
  {
    found_element_to_refine = false;
    for (auto bid : block_ids)
      for (auto & elem : mesh_ptr->active_subdomain_elements_ptr_range(bid))
        if (elem->volume() >= _max_element_volume)
        {
          elem->set_refinement_flag(Elem::REFINE);
          found_element_to_refine = true;
        }
    // Refinement needs to be done on all ranks at the same time
    mesh_ptr->comm().max(found_element_to_refine);

    if (found_element_to_refine)
    {
      libMesh::MeshRefinement refinedmesh(*mesh_ptr);
      if (!_enable_neighbor_refinement)
        refinedmesh.face_level_mismatch_limit() = 0;
      refinedmesh.refine_elements();
      refined_on_size = true;
    }
  }

  if (refined_on_size || max > 0)
    mesh_ptr->unset_is_prepared();

  return mesh_ptr;
}

std::unique_ptr<MeshBase>
RefineBlockGenerator::recursive_refine(std::vector<subdomain_id_type> block_ids,
                                       std::unique_ptr<MeshBase> & mesh,
                                       std::vector<unsigned int> refinement,
                                       unsigned int max,
                                       unsigned int ref_step)
{
  if (ref_step == max)
    return dynamic_pointer_cast<MeshBase>(mesh);
  for (std::size_t i = 0; i < block_ids.size(); i++)
  {
    if (refinement[i] > 0 && refinement[i] > ref_step)
    {
      for (const auto & elem : mesh->active_subdomain_elements_ptr_range(block_ids[i]))
        elem->set_refinement_flag(Elem::REFINE);
    }
  }
  libMesh::MeshRefinement refinedmesh(*mesh);
  if (!_enable_neighbor_refinement)
    refinedmesh.face_level_mismatch_limit() = 0;
  refinedmesh.refine_elements();

  ref_step++;
  return recursive_refine(block_ids, mesh, refinement, max, ref_step);
}