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 <cmath>
8 : #include <limits>
9 : #include <tuple>
10 :
11 : #include "DataStructures/DataBox/DataBox.hpp"
12 : #include "IO/Observer/ObserverComponent.hpp"
13 : #include "IO/Observer/ReductionActions.hpp"
14 : #include "NumericalAlgorithms/SphericalHarmonics/Spherepack.hpp"
15 : #include "NumericalAlgorithms/Strahlkorper/Strahlkorper.hpp"
16 : #include "NumericalAlgorithms/Strahlkorper/Tags.hpp"
17 : #include "Parallel/GlobalCache.hpp"
18 : #include "Parallel/Invoke.hpp"
19 : #include "Parallel/ParallelComponentHelpers.hpp"
20 : #include "ParallelAlgorithms/ApparentHorizonFinder/FastFlow.hpp"
21 : #include "ParallelAlgorithms/ApparentHorizonFinder/Protocols/Callback.hpp"
22 : #include "ParallelAlgorithms/ApparentHorizonFinder/Tags.hpp"
23 : #include "PointwiseFunctions/GeneralRelativity/Surfaces/Tags.hpp"
24 : #include "Utilities/Gsl.hpp"
25 : #include "Utilities/PrettyType.hpp"
26 : #include "Utilities/ProtocolHelpers.hpp"
27 :
28 : /// \cond
29 : namespace Frame {
30 : struct Grid;
31 : struct Distorted;
32 : struct Inertial;
33 : } // namespace Frame
34 : /// \endcond
35 :
36 : namespace ah::callbacks {
37 : /*!
38 : * \brief Writes the center of an apparent horizon to disk in both the
39 : * `Frame` template parameter frame and Frame::Inertial frame. Intended to be
40 : * used in the `horizon_find_callbacks` list of a
41 : * `ah::protocols::HorizonMetavars`.
42 : *
43 : * The centers will be written to a subfile with the name
44 : * `/ApparentHorizons/TargetName_Centers.dat` where `TargetName` is the
45 : * pretty_type::name of the \p HorizonMetavars template parameter.
46 : *
47 : * The columns of the dat file are:
48 : * - %Time
49 : * - GridCenter_x
50 : * - GridCenter_y
51 : * - GridCenter_z
52 : * - InertialCenter_x
53 : * - InertialCenter_y
54 : * - InertialCenter_z
55 : *
56 : * The `Frame` template parameter must be either `::Frame::Grid` or
57 : * `::Frame::Distorted`. Even though the template parameter can be
58 : * `::Frame::Distorted`, we still write `GridCenter_?` because the centers of
59 : * the objects are the same in the Grid and Distorted frames.
60 : *
61 : * \note Requires `ylm::Tags::Strahlkorper<Frame>` and
62 : * `ylm::Tags::CartesianCoords<Frame::Inertial>` and
63 : * `ylm::Tags::EuclideanAreaElement<Frame>` to be in the DataBox of the horizon
64 : * finder.
65 : */
66 : template <typename HorizonMetavars>
67 1 : struct ObserveCenters : tt::ConformsTo<ah::protocols::Callback> {
68 : template <typename DbTags, typename Metavariables>
69 0 : static void apply(const db::DataBox<DbTags>& box,
70 : Parallel::GlobalCache<Metavariables>& cache,
71 : const FastFlow::Status /*status*/) {
72 : using frame = typename HorizonMetavars::frame;
73 : static_assert(std::is_same_v<frame, ::Frame::Grid> or
74 : std::is_same_v<frame, ::Frame::Distorted>,
75 : "Frame must be either Grid or Distorted.");
76 : using HorizonTag = ylm::Tags::Strahlkorper<frame>;
77 : using CoordsTag = ylm::Tags::CartesianCoords<::Frame::Inertial>;
78 : using EuclideanAreaElementTag = ylm::Tags::EuclideanAreaElement<frame>;
79 : static_assert(db::tag_is_retrievable_v<HorizonTag, db::DataBox<DbTags>>,
80 : "DataBox must contain ylm::Tags::Strahlkorper<Frame>");
81 : static_assert(db::tag_is_retrievable_v<CoordsTag, db::DataBox<DbTags>>,
82 : "DataBox must contain "
83 : "ylm::Tags::CartesianCoords<Frame::Inertial>");
84 : static_assert(
85 : db::tag_is_retrievable_v<EuclideanAreaElementTag, db::DataBox<DbTags>>,
86 : "DataBox must contain ylm::Tags::EuclideanAreaElement<Frame>");
87 :
88 : // Only print the centers if we want to.
89 : if (not Parallel::get<ah::Tags::ObserveCenters>(cache)) {
90 : return;
91 : }
92 :
93 : const auto& grid_horizon = db::get<HorizonTag>(box);
94 : const std::array<double, 3> grid_center = grid_horizon.physical_center();
95 :
96 : // computes the inertial center to be the average value of the
97 : // inertial coordinates over the Strahlkorper, where the average is
98 : // computed by a surface integral.
99 : // Note that we use the Euclidean area element here, since we are trying
100 : // to find a geometric center of a surface without regard to GR.
101 : const auto& inertial_coords = db::get<CoordsTag>(box);
102 : const auto& area_element = db::get<EuclideanAreaElementTag>(box);
103 : std::array<double, 3> inertial_center =
104 : make_array<3>(std::numeric_limits<double>::signaling_NaN());
105 : auto integrand = make_with_value<Scalar<DataVector>>(get(area_element), 0.);
106 : const double denominator = grid_horizon.ylm_spherepack().definite_integral(
107 : get(area_element).data());
108 : for (size_t i = 0; i < 3; ++i) {
109 : get(integrand) = get(area_element) * inertial_coords.get(i);
110 : gsl::at(inertial_center, i) =
111 : grid_horizon.ylm_spherepack().definite_integral(
112 : get(integrand).data()) /
113 : denominator;
114 : }
115 :
116 : // time, grid_x, grid_y, grid_z, inertial_x, inertial_y, inertial_z
117 : const auto& current_time = db::get<ah::Tags::CurrentTime>(box).value();
118 : const auto center_tuple = std::make_tuple(
119 : current_time.id, grid_center[0], grid_center[1], grid_center[2],
120 : inertial_center[0], inertial_center[1], inertial_center[2]);
121 :
122 : auto& observer_writer_proxy = Parallel::get_parallel_component<
123 : observers::ObserverWriter<Metavariables>>(cache);
124 :
125 : const std::string subfile_path{"/ApparentHorizons/" +
126 : HorizonMetavars::name() + "_Centers"};
127 :
128 : Parallel::threaded_action<
129 : observers::ThreadedActions::WriteReductionDataRow>(
130 : // Node 0 is always the writer
131 : observer_writer_proxy[0], subfile_path, legend_, center_tuple);
132 : }
133 :
134 : private:
135 0 : const static inline std::vector<std::string> legend_{
136 : {"Time", "GridCenter_x", "GridCenter_y", "GridCenter_z",
137 : "InertialCenter_x", "InertialCenter_y", "InertialCenter_z"}};
138 : };
139 : } // namespace ah::callbacks
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