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