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 <cstdint>
       8             : #include <optional>
       9             : 
      10             : #include "DataStructures/TaggedVariant.hpp"
      11             : #include "Options/String.hpp"
      12             : #include "Time/StepperErrorEstimate.hpp"
      13             : #include "Time/TimeStepId.hpp"
      14             : #include "Time/TimeSteppers/TimeStepper.hpp"
      15             : #include "Utilities/Gsl.hpp"
      16             : #include "Utilities/Serialization/CharmPupable.hpp"
      17             : #include "Utilities/TMPL.hpp"
      18             : 
      19             : /// \cond
      20             : struct StepperErrorTolerances;
      21             : class TimeDelta;
      22             : namespace TimeSteppers {
      23             : template <typename T>
      24             : class ConstUntypedHistory;
      25             : template <typename T>
      26             : class MutableUntypedHistory;
      27             : }  // namespace TimeSteppers
      28             : /// \endcond
      29             : 
      30             : namespace TimeSteppers {
      31             : 
      32             : /// \ingroup TimeSteppersGroup
      33             : ///
      34             : /// A "strong stability-preserving" 3rd-order Runge-Kutta
      35             : /// time-stepper, as described in \cite HesthavenWarburton section
      36             : /// 5.7.
      37             : ///
      38             : /// The CFL factor/stable step size is 1.25637266330916.
      39             : ///
      40             : /// \note The time stepper is only strong-stability-preserving for
      41             : /// time steps not exceeding 1.0, i.e., slightly less than 0.8 times
      42             : /// the stable step.
      43           1 : class Rk3HesthavenSsp : public TimeStepper {
      44             :  public:
      45           0 :   using options = tmpl::list<>;
      46           0 :   static constexpr Options::String help = {
      47             :       "A third-order strong stability-preserving Runge-Kutta time-stepper."};
      48             : 
      49           0 :   Rk3HesthavenSsp() = default;
      50           0 :   Rk3HesthavenSsp(const Rk3HesthavenSsp&) = default;
      51           0 :   Rk3HesthavenSsp& operator=(const Rk3HesthavenSsp&) = default;
      52           0 :   Rk3HesthavenSsp(Rk3HesthavenSsp&&) = default;
      53           0 :   Rk3HesthavenSsp& operator=(Rk3HesthavenSsp&&) = default;
      54           0 :   ~Rk3HesthavenSsp() override = default;
      55             : 
      56           0 :   WRAPPED_PUPable_decl_template(Rk3HesthavenSsp);  // NOLINT
      57             : 
      58           0 :   explicit Rk3HesthavenSsp(CkMigrateMessage* /*unused*/) {}
      59             : 
      60           1 :   variants::TaggedVariant<Tags::FixedOrder, Tags::VariableOrder> order()
      61             :       const override;
      62             : 
      63           1 :   double stable_step() const override;
      64             : 
      65           1 :   bool monotonic() const override;
      66             : 
      67           1 :   uint64_t number_of_substeps() const override;
      68             : 
      69           1 :   uint64_t number_of_substeps_for_error() const override;
      70             : 
      71           1 :   size_t number_of_past_steps() const override;
      72             : 
      73           1 :   TimeStepId next_time_id(const TimeStepId& current_id,
      74             :                           const TimeDelta& time_step) const override;
      75             : 
      76           1 :   TimeStepId next_time_id_for_error(const TimeStepId& current_id,
      77             :                                     const TimeDelta& time_step) const override;
      78             : 
      79             :  private:
      80             :   template <typename T>
      81           0 :   void update_u_impl(gsl::not_null<T*> u, const ConstUntypedHistory<T>& history,
      82             :                      const TimeDelta& time_step) const;
      83             : 
      84             :   template <typename T>
      85           0 :   std::optional<StepperErrorEstimate> update_u_impl(
      86             :       gsl::not_null<T*> u, const ConstUntypedHistory<T>& history,
      87             :       const TimeDelta& time_step,
      88             :       const std::optional<StepperErrorTolerances>& tolerances) const;
      89             : 
      90             :   template <typename T>
      91           0 :   void clean_history_impl(const MutableUntypedHistory<T>& history) const;
      92             : 
      93             :   template <typename T>
      94           0 :   bool dense_update_u_impl(gsl::not_null<T*> u,
      95             :                            const ConstUntypedHistory<T>& history,
      96             :                            double time) const;
      97             : 
      98             :   template <typename T>
      99           0 :   bool can_change_step_size_impl(const TimeStepId& time_id,
     100             :                                  const ConstUntypedHistory<T>& history) const;
     101             : 
     102             :   TIME_STEPPER_DECLARE_OVERLOADS
     103             : };
     104             : 
     105           0 : inline bool constexpr operator==(const Rk3HesthavenSsp& /*lhs*/,
     106             :                                  const Rk3HesthavenSsp& /*rhs*/) {
     107             :   return true;
     108             : }
     109             : 
     110           0 : inline bool constexpr operator!=(const Rk3HesthavenSsp& /*lhs*/,
     111             :                                  const Rk3HesthavenSsp& /*rhs*/) {
     112             :   return false;
     113             : }
     114             : }  // namespace TimeSteppers