WaterSaturationCurveIAPWSIF97Region4.h

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// SPDX-FileCopyrightText: Copyright (c) OpenGeoSys Community (opengeosys.org)
// SPDX-License-Identifier: BSD-3-Clause
 
#pragma once
 
#include <array>
#include <cmath>
 
namespace MaterialPropertyLib::IAPWSIF97Region4
{

inline double waterSaturationTemperature(double const pressure)
{
    static constexpr std::array n = {0.11670521452767e4,  -0.72421316703206e6,
                                     -0.17073846940092e2, 0.12020824702470e5,
                                     -0.32325550322333e7, 0.14915108613530e2,
                                     -0.48232657361591e4, 0.40511340542057e6,
                                     -0.23855557567849,   0.65017534844798e3};
 
    static constexpr double p_c = 1e6;
 
    double const beta2 = std::sqrt(pressure / p_c);
    double const beta = std::sqrt(beta2);
 
    double const E = beta2 + n[2] * beta + n[5];
    double const F = n[0] * beta2 + n[3] * beta + n[6];
    double const G = n[1] * beta2 + n[4] * beta + n[7];
 
    double const D = 2 * G / (-F - std::sqrt(F * F - 4 * E * G));
 
    double const n10pD = n[9] + D;
 
    return (n10pD - std::sqrt(n10pD * n10pD - 4 * (n[8] + n[9] * D))) / 2;
}
}  // namespace MaterialPropertyLib::IAPWSIF97Region4