barotropic_equation_of_state_isothermal.h

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//
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
// Copyright (C) 2025 - 2026 by the ryujin authors
//
 
#pragma once
 
#include <ryujin/base/compile_time_options.h>
#include <ryujin/euler_barotropic/barotropic_equation_of_state.h>
 
namespace ryujin
{
  namespace BarotropicEquationsOfState
  {
    class Isothermal : public BarotropicEquationOfState
    {
    public:
      Isothermal(const std::string &subsection)
          : BarotropicEquationOfState("isothermal", subsection)
      {
        speed_of_sound_ = 2.;
        add_parameter("speed of sound",
                      speed_of_sound_,
                      "The speed of sound of the isothermal equation of state");
      }
 
      double specific_internal_energy(double rho) const final
      {
        return speed_of_sound_ * speed_of_sound_ * std::log(rho);
      }
 
      double pressure(double rho) const final
      {
        return speed_of_sound_ * speed_of_sound_ * rho;
      }
 
      double speed_of_sound(double /*rho*/) const final
      {
        return speed_of_sound_;
      }
 
    private:
      double speed_of_sound_;
    };
  } // namespace BarotropicEquationsOfState
} // namespace ryujin