initial_state_ritter_dam_break.h

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//
// SPDX-License-Identifier: Apache-2.0
// [LANL Copyright Statement]
// Copyright (C) 2022 - 2025 by the ryujin authors
// Copyright (C) 2023 - 2024 by Triad National Security, LLC
//
 
#pragma once
 
#include <compile_time_options.h>
 
#include <initial_state_library.h>
 
namespace ryujin
{
  namespace ShallowWaterInitialStates
  {
    template <typename Description, int dim, typename Number>
    class RitterDamBreak : public InitialState<Description, dim, Number>
    {
    public:
      using HyperbolicSystem = typename Description::HyperbolicSystem;
      using View = typename HyperbolicSystem::template View<dim, Number>;
      using state_type = typename View::state_type;
 
      RitterDamBreak(const HyperbolicSystem &hyperbolic_system,
                     const std::string subsection)
          : InitialState<Description, dim, Number>("ritter dam break",
                                                   subsection)
          , hyperbolic_system_(hyperbolic_system)
      {
        dealii::ParameterAcceptor::parse_parameters_call_back.connect(
            std::bind(&RitterDamBreak::parse_parameters_callback, this));
 
        t_initial_ = 0.1;
        this->add_parameter("time initial",
                            t_initial_,
                            "Time at which initial state is prescribed");
 
        left_depth = 0.005;
        this->add_parameter("left water depth",
                            left_depth,
                            "Depth of water to the left of pseudo-dam (x<0)");
      }
 
      void parse_parameters_callback()
      {
        AssertThrow(t_initial_ > 0.,
                    dealii::ExcMessage("Expansion must be computed at an "
                                       "initial time greater than 0."));
      }
 
      state_type compute(const dealii::Point<dim> &point, Number t) final
      {
        const auto view = hyperbolic_system_.template view<dim, Number>();
        const auto g = view.gravity();
 
        const auto x = point[0];
 
        const Number aL = std::sqrt(g * left_depth);
        const Number xA = -(t + t_initial_) * aL;
        const Number xB = Number(2.) * (t + t_initial_) * aL;
 
        const Number tmp = aL - x / (2. * (t + t_initial_));
 
        const Number h_expansion = 4. / (9. * g) * tmp * tmp;
        const Number v_expansion = 2. / 3. * (x / (t + t_initial_) + aL);
 
        if (x <= xA)
          return state_type{{left_depth, Number(0.)}};
        else if (x <= xB)
          return state_type{{h_expansion, h_expansion * v_expansion}};
        else
          return state_type{{Number(0.), Number(0.)}};
      }
 
      /* Default bathymetry of 0 */
 
    private:
      const HyperbolicSystem &hyperbolic_system_;
 
      Number t_initial_;
      Number left_depth;
    };
 
  } // namespace ShallowWaterInitialStates
} // namespace ryujin