flux.h

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//
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
// Copyright (C) 2023 - 2026 by the ryujin authors
//
 
#pragma once
 
#include <ryujin/base/compile_time_options.h>
#include <ryujin/base/convenience_macros.h>
 
#include <deal.II/base/function.h>
#include <deal.II/base/parameter_acceptor.h>
 
#include <string>
 
namespace ryujin
{
  class Flux : public dealii::ParameterAcceptor
  {
  public:
    Flux(const std::string &name, const std::string &subsection)
        /* simply default to three components... */
        : ParameterAcceptor(subsection + "/" + name)
        , name_(name)
    {
      derivative_approximation_delta_ =
          1.e4 * std::numeric_limits<double>::epsilon();
    }
 
 
    virtual double value(double state, unsigned int direction) const = 0;
 
 
    virtual double gradient(double state, unsigned int direction) const = 0;
 
    ACCESSOR_READ_ONLY(name);
 
    ACCESSOR_READ_ONLY(derivative_approximation_delta)
 
    
    ACCESSOR_READ_ONLY(flux_formula);
 
  protected:
    double derivative_approximation_delta_;
    std::string flux_formula_;
 
  private:
    const std::string name_;
  };
} // namespace ryujin