SpECTRE Documentation Coverage Report
Current view: top level - Evolution/Systems/ScalarAdvection/Subcell - TimeDerivative.hpp Hit Total Coverage
Commit: 817e13c5144619b701c7cd870655d8dbf94ab8ce Lines: 1 3 33.3 %
Date: 2024-07-19 22:17:05
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          Line data    Source code
       1           0 : // Distributed under the MIT License.
       2             : // See LICENSE.txt for details.
       3             : 
       4             : #pragma once
       5             : 
       6             : #include <array>
       7             : #include <cstddef>
       8             : #include <optional>
       9             : #include <type_traits>
      10             : 
      11             : #include "DataStructures/DataBox/AsAccess.hpp"
      12             : #include "DataStructures/DataBox/DataBox.hpp"
      13             : #include "DataStructures/DataBox/PrefixHelpers.hpp"
      14             : #include "DataStructures/DataBox/Prefixes.hpp"
      15             : #include "DataStructures/DataVector.hpp"
      16             : #include "DataStructures/Tensor/Tensor.hpp"
      17             : #include "DataStructures/Variables.hpp"
      18             : #include "Domain/CoordinateMaps/Tags.hpp"
      19             : #include "Domain/Structure/Element.hpp"
      20             : #include "Domain/Tags.hpp"
      21             : #include "Evolution/BoundaryCorrectionTags.hpp"
      22             : #include "Evolution/DgSubcell/CartesianFluxDivergence.hpp"
      23             : #include "Evolution/DgSubcell/ComputeBoundaryTerms.hpp"
      24             : #include "Evolution/DgSubcell/CorrectPackagedData.hpp"
      25             : #include "Evolution/DgSubcell/Tags/Coordinates.hpp"
      26             : #include "Evolution/DgSubcell/Tags/Jacobians.hpp"
      27             : #include "Evolution/DgSubcell/Tags/Mesh.hpp"
      28             : #include "Evolution/DgSubcell/Tags/OnSubcellFaces.hpp"
      29             : #include "Evolution/DiscontinuousGalerkin/Actions/PackageDataImpl.hpp"
      30             : #include "Evolution/DiscontinuousGalerkin/MortarTags.hpp"
      31             : #include "Evolution/Systems/ScalarAdvection/FiniteDifference/Reconstructor.hpp"
      32             : #include "Evolution/Systems/ScalarAdvection/FiniteDifference/Tags.hpp"
      33             : #include "Evolution/Systems/ScalarAdvection/Fluxes.hpp"
      34             : #include "Evolution/Systems/ScalarAdvection/Subcell/ComputeFluxes.hpp"
      35             : #include "Evolution/Systems/ScalarAdvection/System.hpp"
      36             : #include "NumericalAlgorithms/Spectral/Mesh.hpp"
      37             : #include "Utilities/CallWithDynamicType.hpp"
      38             : #include "Utilities/ErrorHandling/Assert.hpp"
      39             : #include "Utilities/Gsl.hpp"
      40             : #include "Utilities/MakeArray.hpp"
      41             : 
      42             : namespace ScalarAdvection::subcell {
      43             : /*!
      44             :  * \brief Compute the time derivative on the subcell grid using FD
      45             :  * reconstruction.
      46             :  *
      47             :  * The code makes the following unchecked assumptions:
      48             :  * - Assumes Cartesian coordinates with a diagonal Jacobian matrix
      49             :  * from the logical to the inertial frame
      50             :  * - Assumes the mesh is not moving (grid and inertial frame are the same)
      51             :  */
      52             : template <size_t Dim>
      53           1 : struct TimeDerivative {
      54             :   template <typename DbTagsList>
      55           0 :   static void apply(const gsl::not_null<db::DataBox<DbTagsList>*> box) {
      56             :     ASSERT((db::get<::domain::CoordinateMaps::Tags::CoordinateMap<
      57             :                 Dim, Frame::Grid, Frame::Inertial>>(*box))
      58             :                .is_identity(),
      59             :            "Do not yet support moving mesh with DG-subcell.");
      60             :     // subcell is currently not supported for external boundary elements
      61             :     const Element<Dim>& element = db::get<domain::Tags::Element<Dim>>(*box);
      62             :     ASSERT(element.external_boundaries().size() == 0,
      63             :            "Can't have external boundaries right now with subcell. ElementID "
      64             :                << element.id());
      65             : 
      66             :     using evolved_vars_tags = typename System<Dim>::variables_tag::tags_list;
      67             :     using fluxes_tags = typename Fluxes<Dim>::return_tags;
      68             : 
      69             :     // The copy of Mesh is intentional to avoid a GCC-7 internal compiler error.
      70             :     const Mesh<Dim> subcell_mesh =
      71             :         db::get<evolution::dg::subcell::Tags::Mesh<Dim>>(*box);
      72             :     ASSERT(
      73             :         subcell_mesh == Mesh<Dim>(subcell_mesh.extents(0),
      74             :                                   subcell_mesh.basis(0),
      75             :                                   subcell_mesh.quadrature(0)),
      76             :         "The subcell/FD mesh must be isotropic for the FD time derivative but "
      77             :         "got "
      78             :             << subcell_mesh);
      79             : 
      80             :     const size_t num_reconstructed_pts =
      81             :         (subcell_mesh.extents(0) + 1) *
      82             :         subcell_mesh.extents().slice_away(0).product();
      83             : 
      84             :     const ScalarAdvection::fd::Reconstructor<Dim>& recons =
      85             :         db::get<ScalarAdvection::fd::Tags::Reconstructor<Dim>>(*box);
      86             : 
      87             :     const auto& boundary_correction =
      88             :         db::get<evolution::Tags::BoundaryCorrection<System<Dim>>>(*box);
      89             :     using derived_boundary_corrections =
      90             :         typename std::decay_t<decltype(boundary_correction)>::creatable_classes;
      91             : 
      92             :     // Variables to store the boundary correction terms on FD subinterfaces
      93             :     std::array<Variables<evolved_vars_tags>, Dim> fd_boundary_corrections{};
      94             : 
      95             :     // package the data and compute the boundary correction
      96             :     tmpl::for_each<derived_boundary_corrections>([&boundary_correction,
      97             :                                                   &fd_boundary_corrections,
      98             :                                                   &box, &element,
      99             :                                                   &num_reconstructed_pts,
     100             :                                                   &recons, &subcell_mesh](
     101             :                                                      auto
     102             :                                                          derived_correction_v) {
     103             :       using derived_correction =
     104             :           tmpl::type_from<decltype(derived_correction_v)>;
     105             :       if (typeid(boundary_correction) == typeid(derived_correction)) {
     106             :         using dg_package_field_tags =
     107             :             typename derived_correction::dg_package_field_tags;
     108             :         using dg_package_data_temporary_tags =
     109             :             typename derived_correction::dg_package_data_temporary_tags;
     110             :         using dg_package_data_argument_tags =
     111             :             tmpl::append<evolved_vars_tags, fluxes_tags,
     112             :                          dg_package_data_temporary_tags>;
     113             : 
     114             :         // Variables that need to be reconstructed for dg_package_data()
     115             :         auto package_data_argvars_lower_face = make_array<Dim>(
     116             :             Variables<dg_package_data_argument_tags>(num_reconstructed_pts));
     117             :         auto package_data_argvars_upper_face = make_array<Dim>(
     118             :             Variables<dg_package_data_argument_tags>(num_reconstructed_pts));
     119             : 
     120             :         // Reconstruct the fields on interfaces
     121             :         call_with_dynamic_type<void, typename ScalarAdvection::fd::
     122             :                                          Reconstructor<Dim>::creatable_classes>(
     123             :             &recons,
     124             :             [&box, &package_data_argvars_lower_face,
     125             :              &package_data_argvars_upper_face](const auto& reconstructor) {
     126             :               db::apply<typename std::decay_t<decltype(
     127             :                   *reconstructor)>::reconstruction_argument_tags>(
     128             :                   [&package_data_argvars_lower_face,
     129             :                    &package_data_argvars_upper_face,
     130             :                    &reconstructor](const auto&... args) {
     131             :                     reconstructor->reconstruct(
     132             :                         make_not_null(&package_data_argvars_lower_face),
     133             :                         make_not_null(&package_data_argvars_upper_face),
     134             :                         args...);
     135             :                   },
     136             :                   *box);
     137             :             });
     138             : 
     139             :         // copy over the face values of the velocity field
     140             :         {
     141             :           using tag = ::ScalarAdvection::Tags::VelocityField<Dim>;
     142             :           const auto& velocity_on_face =
     143             :               db::get<evolution::dg::subcell::Tags::OnSubcellFaces<tag, Dim>>(
     144             :                   *box);
     145             :           for (size_t d = 0; d < Dim; ++d) {
     146             :             get<tag>(gsl::at(package_data_argvars_lower_face, d)) =
     147             :                 gsl::at(velocity_on_face, d);
     148             :             get<tag>(gsl::at(package_data_argvars_upper_face, d)) =
     149             :                 gsl::at(velocity_on_face, d);
     150             :           }
     151             :         }
     152             : 
     153             :         // Variables to store packaged data. Allocate outside of loop to
     154             :         // reduce allocations
     155             :         Variables<dg_package_field_tags> upper_packaged_data{
     156             :             num_reconstructed_pts};
     157             :         Variables<dg_package_field_tags> lower_packaged_data{
     158             :             num_reconstructed_pts};
     159             : 
     160             :         for (size_t dim = 0; dim < Dim; ++dim) {
     161             :           auto& vars_upper_face = gsl::at(package_data_argvars_upper_face, dim);
     162             :           auto& vars_lower_face = gsl::at(package_data_argvars_lower_face, dim);
     163             : 
     164             :           // Compute fluxes on each faces
     165             :           ScalarAdvection::subcell::compute_fluxes<Dim>(
     166             :               make_not_null(&vars_upper_face));
     167             :           ScalarAdvection::subcell::compute_fluxes<Dim>(
     168             :               make_not_null(&vars_lower_face));
     169             : 
     170             :           // Note that we use the sign convention on the normal vectors to
     171             :           // be compatible with DG.
     172             :           tnsr::i<DataVector, Dim, Frame::Inertial> lower_outward_conormal{
     173             :               num_reconstructed_pts, 0.0};
     174             :           lower_outward_conormal.get(dim) = 1.0;
     175             :           tnsr::i<DataVector, Dim, Frame::Inertial> upper_outward_conormal{
     176             :               num_reconstructed_pts, 0.0};
     177             :           upper_outward_conormal.get(dim) = -1.0;
     178             : 
     179             :           // Compute the packaged data
     180             :           evolution::dg::Actions::detail::dg_package_data<System<Dim>>(
     181             :               make_not_null(&upper_packaged_data),
     182             :               dynamic_cast<const derived_correction&>(boundary_correction),
     183             :               vars_upper_face, upper_outward_conormal, {std::nullopt}, *box,
     184             :               typename derived_correction::dg_package_data_volume_tags{},
     185             :               dg_package_data_argument_tags{});
     186             :           evolution::dg::Actions::detail::dg_package_data<System<Dim>>(
     187             :               make_not_null(&lower_packaged_data),
     188             :               dynamic_cast<const derived_correction&>(boundary_correction),
     189             :               vars_lower_face, lower_outward_conormal, {std::nullopt}, *box,
     190             :               typename derived_correction::dg_package_data_volume_tags{},
     191             :               dg_package_data_argument_tags{});
     192             : 
     193             :           // Now need to check if any of our neighbors are doing DG, because
     194             :           // if so then we need to use whatever boundary data they sent
     195             :           // instead of what we computed locally.
     196             :           //
     197             :           // Note: We could check this beforehand to avoid the extra work of
     198             :           // reconstruction and flux computations at the boundaries.
     199             :           evolution::dg::subcell::correct_package_data<true>(
     200             :               make_not_null(&lower_packaged_data),
     201             :               make_not_null(&upper_packaged_data), dim, element, subcell_mesh,
     202             :               db::get<evolution::dg::Tags::MortarData<Dim>>(*box), 0);
     203             : 
     204             :           // Compute the corrections on the faces. We only need to compute this
     205             :           // once because we can just flip the normal vectors then
     206             :           gsl::at(fd_boundary_corrections, dim)
     207             :               .initialize(num_reconstructed_pts);
     208             :           evolution::dg::subcell::compute_boundary_terms(
     209             :               make_not_null(&gsl::at(fd_boundary_corrections, dim)),
     210             :               dynamic_cast<const derived_correction&>(boundary_correction),
     211             :               upper_packaged_data, lower_packaged_data, db::as_access(*box),
     212             :               typename derived_correction::dg_boundary_terms_volume_tags{});
     213             :         }
     214             :       }
     215             :     });
     216             : 
     217             :     std::array<double, Dim> one_over_delta_xi{};
     218             :     {
     219             :       const tnsr::I<DataVector, Dim, Frame::ElementLogical>&
     220             :           cell_centered_logical_coords =
     221             :               db::get<evolution::dg::subcell::Tags::Coordinates<
     222             :                   Dim, Frame::ElementLogical>>(*box);
     223             : 
     224             :       for (size_t i = 0; i < Dim; ++i) {
     225             :         // Note: assumes isotropic extents
     226             :         gsl::at(one_over_delta_xi, i) =
     227             :             1.0 / (get<0>(cell_centered_logical_coords)[1] -
     228             :                    get<0>(cell_centered_logical_coords)[0]);
     229             :       }
     230             :     }
     231             : 
     232             :     // Now compute the actual time derivative
     233             :     using dt_variables_tag =
     234             :         db::add_tag_prefix<::Tags::dt, typename System<Dim>::variables_tag>;
     235             :     const size_t num_pts = subcell_mesh.number_of_grid_points();
     236             :     db::mutate<dt_variables_tag>(
     237             :         [&num_pts, &fd_boundary_corrections, &subcell_mesh, &one_over_delta_xi](
     238             :             const auto dt_vars_ptr,
     239             :             const InverseJacobian<DataVector, Dim, Frame::ElementLogical,
     240             :                                   Frame::Grid>&
     241             :                 cell_centered_logical_to_grid_inv_jacobian) {
     242             :           dt_vars_ptr->initialize(num_pts, 0.0);
     243             :           auto& dt_u =
     244             :               get<::Tags::dt<::ScalarAdvection::Tags::U>>(*dt_vars_ptr);
     245             : 
     246             :           for (size_t dim = 0; dim < Dim; ++dim) {
     247             :             Scalar<DataVector>& u_correction = get<::ScalarAdvection ::Tags::U>(
     248             :                 gsl::at(fd_boundary_corrections, dim));
     249             :             evolution::dg::subcell::add_cartesian_flux_divergence(
     250             :                 make_not_null(&get(dt_u)), gsl::at(one_over_delta_xi, dim),
     251             :                 cell_centered_logical_to_grid_inv_jacobian.get(dim, dim),
     252             :                 get(u_correction), subcell_mesh.extents(), dim);
     253             :           }
     254             :         },
     255             :         box,
     256             :         db::get<evolution::dg::subcell::fd::Tags::InverseJacobianLogicalToGrid<
     257             :             Dim>>(*box));
     258             :   }
     259             : };
     260             : }  // namespace ScalarAdvection::subcell

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