SaturationExponential.cpp

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// SPDX-FileCopyrightText: Copyright (c) OpenGeoSys Community (opengeosys.org)
// SPDX-License-Identifier: BSD-3-Clause
 
#include "SaturationExponential.h"
 
#include <algorithm>
#include <cmath>
 
#include "MaterialLib/MPL/Medium.h"
#include "MathLib/MathTools.h"
 
namespace MaterialPropertyLib
{
SaturationExponential::SaturationExponential(
    std::string name,
    const double residual_liquid_saturation,
    const double residual_gas_saturation,
    const double p_cap_max,
    const double exponent)
    : residual_liquid_saturation_(residual_liquid_saturation),
      residual_gas_saturation_(residual_gas_saturation),
      p_cap_max_(p_cap_max),
      exponent_(exponent)
{
    name_ = std::move(name);
    if (p_cap_max_ <= 0.)
    {
        OGS_FATAL(
            "Reference capillary pressure must be positive in "
            "MPL::SaturationExponential.");
    }
};
 
PropertyDataType SaturationExponential::value(
    VariableArray const& variable_array,
    ParameterLib::SpatialPosition const& /*pos*/, double const /*t*/,
    double const /*dt*/) const
{
    const double p_cap = variable_array.capillary_pressure;
 
    const double S_res = residual_liquid_saturation_;
    const double S_max = 1. - residual_gas_saturation_;
 
    const double pc = std::clamp(p_cap, 0., p_cap_max_);
    const double S_e = 1. - std::pow(pc / p_cap_max_, exponent_);
    return S_e * (S_max - S_res) + S_res;
}
 
PropertyDataType SaturationExponential::dValue(
    VariableArray const& variable_array, Variable const variable,
    ParameterLib::SpatialPosition const& /*pos*/, double const /*t*/,
    double const /*dt*/) const
{
    if (variable != Variable::capillary_pressure)
    {
        OGS_FATAL(
            "SaturationExponential::dValue is implemented for derivatives with "
            "respect to capillary pressure only.");
    }
 
    const double p_cap = variable_array.capillary_pressure;
 
    const double S_res = residual_liquid_saturation_;
    const double S_max = 1. - residual_gas_saturation_;
 
    if ((p_cap > p_cap_max_) || (p_cap <= 0.))
    {
        return 0.;
    }
    return (exponent_ / p_cap) * (S_res - S_max) *
           std::pow(p_cap / p_cap_max_, exponent_);
}
 
PropertyDataType SaturationExponential::d2Value(
    VariableArray const& /*variable_array*/, Variable const /*variable1*/,
    Variable const /*variable2*/, ParameterLib::SpatialPosition const& /*pos*/,
    double const /*t*/, double const /*dt*/) const
{
    OGS_FATAL("SaturationExponential::d2Value() is not implemented.");
}
 
}  // namespace MaterialPropertyLib