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/CoordinateMaps/Tags.hpp"
20 : #include "Domain/Structure/Element.hpp"
21 : #include "Domain/Tags.hpp"
22 : #include "Evolution/BoundaryCorrection.hpp"
23 : #include "Evolution/BoundaryCorrectionTags.hpp"
24 : #include "Evolution/DgSubcell/CartesianFluxDivergence.hpp"
25 : #include "Evolution/DgSubcell/ComputeBoundaryTerms.hpp"
26 : #include "Evolution/DgSubcell/CorrectPackagedData.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/DgSubcell/Tags/OnSubcellFaces.hpp"
31 : #include "Evolution/DiscontinuousGalerkin/Actions/PackageDataImpl.hpp"
32 : #include "Evolution/DiscontinuousGalerkin/MortarTags.hpp"
33 : #include "Evolution/Systems/ScalarAdvection/FiniteDifference/Reconstructor.hpp"
34 : #include "Evolution/Systems/ScalarAdvection/FiniteDifference/Tags.hpp"
35 : #include "Evolution/Systems/ScalarAdvection/Fluxes.hpp"
36 : #include "Evolution/Systems/ScalarAdvection/Subcell/ComputeFluxes.hpp"
37 : #include "Evolution/Systems/ScalarAdvection/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 ScalarAdvection::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 : template <size_t Dim>
55 1 : struct TimeDerivative {
56 : template <typename DbTagsList>
57 0 : static void apply(const gsl::not_null<db::DataBox<DbTagsList>*> box) {
58 : using metavariables =
59 : typename std::decay_t<decltype(db::get<Parallel::Tags::Metavariables>(
60 : *box))>;
61 : ASSERT((db::get<::domain::CoordinateMaps::Tags::CoordinateMap<
62 : Dim, Frame::Grid, Frame::Inertial>>(*box))
63 : .is_identity(),
64 : "Do not yet support moving mesh with DG-subcell.");
65 : // subcell is currently not supported for external boundary elements
66 : const Element<Dim>& element = db::get<domain::Tags::Element<Dim>>(*box);
67 : ASSERT(element.external_boundaries().size() == 0,
68 : "Can't have external boundaries right now with subcell. ElementID "
69 : << element.id());
70 :
71 : using evolved_vars_tags = typename System<Dim>::variables_tag::tags_list;
72 : using fluxes_tags = typename Fluxes<Dim>::return_tags;
73 :
74 : // The copy of Mesh is intentional to avoid a GCC-7 internal compiler error.
75 : const Mesh<Dim> subcell_mesh =
76 : db::get<evolution::dg::subcell::Tags::Mesh<Dim>>(*box);
77 : ASSERT(
78 : subcell_mesh == Mesh<Dim>(subcell_mesh.extents(0),
79 : subcell_mesh.basis(0),
80 : subcell_mesh.quadrature(0)),
81 : "The subcell/FD mesh must be isotropic for the FD time derivative but "
82 : "got "
83 : << subcell_mesh);
84 :
85 : const size_t num_reconstructed_pts =
86 : (subcell_mesh.extents(0) + 1) *
87 : subcell_mesh.extents().slice_away(0).product();
88 :
89 : const ScalarAdvection::fd::Reconstructor<Dim>& recons =
90 : db::get<ScalarAdvection::fd::Tags::Reconstructor<Dim>>(*box);
91 :
92 : const auto& boundary_correction =
93 : db::get<evolution::Tags::BoundaryCorrection>(*box);
94 : using derived_boundary_corrections =
95 : tmpl::at<typename metavariables::factory_creation::factory_classes,
96 : evolution::BoundaryCorrection>;
97 :
98 : // Variables to store the boundary correction terms on FD subinterfaces
99 : std::array<Variables<evolved_vars_tags>, Dim> fd_boundary_corrections{};
100 :
101 : // package the data and compute the boundary correction
102 : tmpl::for_each<derived_boundary_corrections>([&boundary_correction,
103 : &fd_boundary_corrections,
104 : &box, &element,
105 : &num_reconstructed_pts,
106 : &recons, &subcell_mesh](
107 : auto
108 : 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_temporary_tags =
115 : typename derived_correction::dg_package_data_temporary_tags;
116 : using dg_package_data_argument_tags =
117 : tmpl::append<evolved_vars_tags, fluxes_tags,
118 : dg_package_data_temporary_tags>;
119 :
120 : // Variables that need to be reconstructed for dg_package_data()
121 : auto package_data_argvars_lower_face = make_array<Dim>(
122 : Variables<dg_package_data_argument_tags>(num_reconstructed_pts));
123 : auto package_data_argvars_upper_face = make_array<Dim>(
124 : Variables<dg_package_data_argument_tags>(num_reconstructed_pts));
125 :
126 : // Reconstruct the fields on interfaces
127 : call_with_dynamic_type<void, typename ScalarAdvection::fd::
128 : Reconstructor<Dim>::creatable_classes>(
129 : &recons,
130 : [&box, &package_data_argvars_lower_face,
131 : &package_data_argvars_upper_face](const auto& reconstructor) {
132 : db::apply<typename std::decay_t<decltype(
133 : *reconstructor)>::reconstruction_argument_tags>(
134 : [&package_data_argvars_lower_face,
135 : &package_data_argvars_upper_face,
136 : &reconstructor](const auto&... args) {
137 : reconstructor->reconstruct(
138 : make_not_null(&package_data_argvars_lower_face),
139 : make_not_null(&package_data_argvars_upper_face),
140 : args...);
141 : },
142 : *box);
143 : });
144 :
145 : // copy over the face values of the velocity field
146 : {
147 : using tag = ::ScalarAdvection::Tags::VelocityField<Dim>;
148 : const auto& velocity_on_face =
149 : db::get<evolution::dg::subcell::Tags::OnSubcellFaces<tag, Dim>>(
150 : *box);
151 : for (size_t d = 0; d < Dim; ++d) {
152 : get<tag>(gsl::at(package_data_argvars_lower_face, d)) =
153 : gsl::at(velocity_on_face, d);
154 : get<tag>(gsl::at(package_data_argvars_upper_face, d)) =
155 : gsl::at(velocity_on_face, d);
156 : }
157 : }
158 :
159 : // Variables to store packaged data. Allocate outside of loop to
160 : // reduce allocations
161 : Variables<dg_package_field_tags> upper_packaged_data{
162 : num_reconstructed_pts};
163 : Variables<dg_package_field_tags> lower_packaged_data{
164 : num_reconstructed_pts};
165 :
166 : for (size_t dim = 0; dim < Dim; ++dim) {
167 : auto& vars_upper_face = gsl::at(package_data_argvars_upper_face, dim);
168 : auto& vars_lower_face = gsl::at(package_data_argvars_lower_face, dim);
169 :
170 : // Compute fluxes on each faces
171 : ScalarAdvection::subcell::compute_fluxes<Dim>(
172 : make_not_null(&vars_upper_face));
173 : ScalarAdvection::subcell::compute_fluxes<Dim>(
174 : make_not_null(&vars_lower_face));
175 :
176 : // Note that we use the sign convention on the normal vectors to
177 : // be compatible with DG.
178 : tnsr::i<DataVector, Dim, Frame::Inertial> lower_outward_conormal{
179 : num_reconstructed_pts, 0.0};
180 : lower_outward_conormal.get(dim) = 1.0;
181 : tnsr::i<DataVector, Dim, Frame::Inertial> upper_outward_conormal{
182 : num_reconstructed_pts, 0.0};
183 : upper_outward_conormal.get(dim) = -1.0;
184 :
185 : // Compute the packaged data
186 : evolution::dg::Actions::detail::dg_package_data<System<Dim>>(
187 : make_not_null(&upper_packaged_data),
188 : dynamic_cast<const derived_correction&>(boundary_correction),
189 : vars_upper_face, upper_outward_conormal, {std::nullopt}, *box,
190 : typename derived_correction::dg_package_data_volume_tags{},
191 : dg_package_data_argument_tags{});
192 : evolution::dg::Actions::detail::dg_package_data<System<Dim>>(
193 : make_not_null(&lower_packaged_data),
194 : dynamic_cast<const derived_correction&>(boundary_correction),
195 : vars_lower_face, lower_outward_conormal, {std::nullopt}, *box,
196 : typename derived_correction::dg_package_data_volume_tags{},
197 : dg_package_data_argument_tags{});
198 :
199 : // Now need to check if any of our neighbors are doing DG, because
200 : // if so then we need to use whatever boundary data they sent
201 : // instead of what we computed locally.
202 : //
203 : // Note: We could check this beforehand to avoid the extra work of
204 : // reconstruction and flux computations at the boundaries.
205 : evolution::dg::subcell::correct_package_data<true>(
206 : make_not_null(&lower_packaged_data),
207 : make_not_null(&upper_packaged_data), dim, element, subcell_mesh,
208 : db::get<evolution::dg::Tags::MortarData<Dim>>(*box), 0);
209 :
210 : // Compute the corrections on the faces. We only need to compute this
211 : // once because we can just flip the normal vectors then
212 : gsl::at(fd_boundary_corrections, dim)
213 : .initialize(num_reconstructed_pts);
214 : evolution::dg::subcell::compute_boundary_terms(
215 : make_not_null(&gsl::at(fd_boundary_corrections, dim)),
216 : dynamic_cast<const derived_correction&>(boundary_correction),
217 : upper_packaged_data, lower_packaged_data, db::as_access(*box),
218 : typename derived_correction::dg_boundary_terms_volume_tags{});
219 : }
220 : }
221 : });
222 :
223 : std::array<double, Dim> one_over_delta_xi{};
224 : {
225 : const tnsr::I<DataVector, Dim, Frame::ElementLogical>&
226 : cell_centered_logical_coords =
227 : db::get<evolution::dg::subcell::Tags::Coordinates<
228 : Dim, Frame::ElementLogical>>(*box);
229 :
230 : for (size_t i = 0; i < Dim; ++i) {
231 : // Note: assumes isotropic extents
232 : gsl::at(one_over_delta_xi, i) =
233 : 1.0 / (get<0>(cell_centered_logical_coords)[1] -
234 : get<0>(cell_centered_logical_coords)[0]);
235 : }
236 : }
237 :
238 : // Now compute the actual time derivative
239 : using dt_variables_tag =
240 : db::add_tag_prefix<::Tags::dt, typename System<Dim>::variables_tag>;
241 : const size_t num_pts = subcell_mesh.number_of_grid_points();
242 : db::mutate<dt_variables_tag>(
243 : [&num_pts, &fd_boundary_corrections, &subcell_mesh, &one_over_delta_xi](
244 : const auto dt_vars_ptr,
245 : const InverseJacobian<DataVector, Dim, Frame::ElementLogical,
246 : Frame::Grid>&
247 : cell_centered_logical_to_grid_inv_jacobian) {
248 : dt_vars_ptr->initialize(num_pts, 0.0);
249 : auto& dt_u =
250 : get<::Tags::dt<::ScalarAdvection::Tags::U>>(*dt_vars_ptr);
251 :
252 : for (size_t dim = 0; dim < Dim; ++dim) {
253 : Scalar<DataVector>& u_correction = get<::ScalarAdvection ::Tags::U>(
254 : gsl::at(fd_boundary_corrections, dim));
255 : evolution::dg::subcell::add_cartesian_flux_divergence(
256 : make_not_null(&get(dt_u)), gsl::at(one_over_delta_xi, dim),
257 : cell_centered_logical_to_grid_inv_jacobian.get(dim, dim),
258 : get(u_correction), subcell_mesh.extents(), dim);
259 : }
260 : },
261 : box,
262 : db::get<evolution::dg::subcell::fd::Tags::InverseJacobianLogicalToGrid<
263 : Dim>>(*box));
264 : }
265 : };
266 : } // namespace ScalarAdvection::subcell
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