Line data    Source code

       1           0 : // Distributed under the MIT License.
       2             : // See LICENSE.txt for details.
       3             : 
       4             : #pragma once
       5             : 
       6             : #include <cstddef>
       7             : #include <pup.h>
       8             : 
       9             : #include "DataStructures/CachedTempBuffer.hpp"
      10             : #include "DataStructures/DataBox/Prefixes.hpp"
      11             : #include "DataStructures/Tensor/Tensor.hpp"
      12             : #include "Elliptic/Systems/Poisson/Tags.hpp"
      13             : #include "NumericalAlgorithms/LinearOperators/PartialDerivatives.hpp"
      14             : #include "Options/String.hpp"
      15             : #include "PointwiseFunctions/InitialDataUtilities/AnalyticSolution.hpp"
      16             : #include "Utilities/ContainerHelpers.hpp"
      17             : #include "Utilities/Gsl.hpp"
      18             : #include "Utilities/TMPL.hpp"
      19             : #include "Utilities/TaggedTuple.hpp"
      20             : 
      21             : namespace Poisson::Solutions {
      22             : 
      23             : namespace detail {
      24             : template <typename DataType, size_t Dim>
      25             : struct MoustacheVariables {
      26             :   using Cache = CachedTempBuffer<
      27             :       Tags::Field,
      28             :       ::Tags::deriv<Tags::Field, tmpl::size_t<Dim>, Frame::Inertial>,
      29             :       ::Tags::Flux<Tags::Field, tmpl::size_t<Dim>, Frame::Inertial>,
      30             :       ::Tags::FixedSource<Tags::Field>>;
      31             : 
      32             :   const tnsr::I<DataType, Dim>& x;
      33             : 
      34             :   void operator()(gsl::not_null<Scalar<DataType>*> field,
      35             :                   gsl::not_null<Cache*> cache, Tags::Field /*meta*/) const;
      36             :   void operator()(gsl::not_null<tnsr::i<DataType, Dim>*> field_gradient,
      37             :                   gsl::not_null<Cache*> cache,
      38             :                   ::Tags::deriv<Tags::Field, tmpl::size_t<Dim>,
      39             :                                 Frame::Inertial> /*meta*/) const;
      40             :   void operator()(gsl::not_null<tnsr::I<DataType, Dim>*> flux_for_field,
      41             :                   gsl::not_null<Cache*> cache,
      42             :                   ::Tags::Flux<Tags::Field, tmpl::size_t<Dim>,
      43             :                                Frame::Inertial> /*meta*/) const;
      44             :   void operator()(gsl::not_null<Scalar<DataType>*> fixed_source_for_field,
      45             :                   gsl::not_null<Cache*> cache,
      46             :                   ::Tags::FixedSource<Tags::Field> /*meta*/) const;
      47             : };
      48             : }  // namespace detail
      49             : 
      50             : /*!
      51             :  * \brief A solution to the Poisson equation with a discontinuous first
      52             :  * derivative.
      53             :  *
      54             :  * \details This implements the solution \f$u(x,y)=x\left(1-x\right)
      55             :  * y\left(1-y\right)\left(\left(x-\frac{1}{2}\right)^2+\left(y-
      56             :  * \frac{1}{2}\right)^2\right)^\frac{3}{2}\f$ to the Poisson equation
      57             :  * in two dimensions, and
      58             :  * \f$u(x)=x\left(1-x\right)\left|x-\frac{1}{2}\right|^3\f$ in one dimension.
      59             :  * Their boundary conditions vanish on the square \f$[0,1]^2\f$ or interval
      60             :  * \f$[0,1]\f$, respectively.
      61             :  *
      62             :  * The corresponding source \f$f=-\Delta u\f$ has a discontinuous first
      63             :  * derivative at \f$\frac{1}{2}\f$. This accomplishes two things:
      64             :  *
      65             :  * - It makes it useful to test the convergence behaviour of our elliptic DG
      66             :  * solver.
      67             :  * - It makes it look like a moustache (at least in 1D).
      68             :  *
      69             :  * This solution is taken from \cite Stamm2010.
      70             :  */
      71             : template <size_t Dim>
      72           1 : class Moustache : public elliptic::analytic_data::AnalyticSolution {
      73             :  public:
      74           0 :   using options = tmpl::list<>;
      75           0 :   static constexpr Options::String help{
      76             :       "A solution with a discontinuous first derivative of its source at 1/2 "
      77             :       "that also happens to look like a moustache. It vanishes at zero and one "
      78             :       "in each dimension"};
      79             : 
      80           0 :   Moustache() = default;
      81           0 :   Moustache(const Moustache&) = default;
      82           0 :   Moustache& operator=(const Moustache&) = default;
      83           0 :   Moustache(Moustache&&) = default;
      84           0 :   Moustache& operator=(Moustache&&) = default;
      85           0 :   ~Moustache() override = default;
      86           0 :   std::unique_ptr<elliptic::analytic_data::AnalyticSolution> get_clone()
      87             :       const override {
      88             :     return std::make_unique<Moustache>(*this);
      89             :   }
      90             : 
      91             :   /// \cond
      92             :   explicit Moustache(CkMigrateMessage* m)
      93             :       : elliptic::analytic_data::AnalyticSolution(m) {}
      94             :   using PUP::able::register_constructor;
      95             :   WRAPPED_PUPable_decl_template(Moustache);  // NOLINT
      96             :   /// \endcond
      97             : 
      98             :   template <typename DataType, typename... RequestedTags>
      99           0 :   tuples::TaggedTuple<RequestedTags...> variables(
     100             :       const tnsr::I<DataType, Dim>& x,
     101             :       tmpl::list<RequestedTags...> /*meta*/) const {
     102             :     using VarsComputer = detail::MoustacheVariables<DataType, Dim>;
     103             :     typename VarsComputer::Cache cache{get_size(*x.begin())};
     104             :     const VarsComputer computer{x};
     105             :     return {cache.get_var(computer, RequestedTags{})...};
     106             :   }
     107             : };
     108             : 
     109             : /// \cond
     110             : template <size_t Dim>
     111             : PUP::able::PUP_ID Moustache<Dim>::my_PUP_ID = 0;  // NOLINT
     112             : /// \endcond
     113             : 
     114             : template <size_t Dim>
     115           0 : constexpr bool operator==(const Moustache<Dim>& /*lhs*/,
     116             :                           const Moustache<Dim>& /*rhs*/) {
     117             :   return true;
     118             : }
     119             : 
     120             : template <size_t Dim>
     121           0 : constexpr bool operator!=(const Moustache<Dim>& lhs,
     122             :                           const Moustache<Dim>& rhs) {
     123             :   return not(lhs == rhs);
     124             : }
     125             : 
     126             : }  // namespace Poisson::Solutions