main.cpp

#include <iostream>
#include <algorithm>
#include <numeric>
#include <valarray>
#include <chrono>
#include <iomanip>

#include "teqp/derivs.hpp"
#include "teqp/models/eos.hpp"
#include "teqp/models/pcsaft.hpp"

void test_vdwMix() {
    // Argon + Xenon
    std::valarray<double> Tc_K = { 150.687, 289.733 };
    std::valarray<double> pc_Pa = { 4863000.0, 5842000.0 };
    vdWEOS<double> vdW(Tc_K, pc_Pa);

    double T = 298.15;
    auto rho = 3.0;
    auto R = get_R_gas<double>();
    auto rhotot = rho;

    const auto rhovec = (Eigen::ArrayXd(2) << rho/2, rho/2).finished();

    auto fPsir = [&vdW](const auto& T, const auto& rhovec) {
        using container = decltype(rhovec);
        auto rhotot_ = std::accumulate(std::begin(rhovec), std::end(rhovec), (decltype(rhovec[0]))0.0);
        auto molefrac = rhovec/rhotot_;
        auto R = forceeval(vdW.R(molefrac));
        return vdW.alphar(T, rhotot_, molefrac)*R*T*rhotot_;
    };
    auto Psir = fPsir(T, rhovec);
    auto dPsirdrho0 = rhovec[0]*derivrhoi(fPsir, T, rhovec, 0);
    auto dPsirdrho1 = rhovec[1]*derivrhoi(fPsir, T, rhovec, 1);
    auto pfromderiv = rho*R*T - Psir + dPsirdrho0 + dPsirdrho1;
    using id = IsochoricDerivatives<decltype(vdW)>;
    auto sr = id::get_splus(vdW, T, rhovec);

    auto t2 = std::chrono::steady_clock::now();
    auto pfromderiv3 = rhotot*R*T + id::get_pr(vdW, T, rhovec);
    auto t3 = std::chrono::steady_clock::now();
    std::cout << std::chrono::duration<double>(t3 - t2).count() << " from isochoric (mix) " << std::endl;
}

int main(){
    test_vdwMix();
    
    std::vector<std::string> names = { "Methane", "Ethane" };
    PCSAFTMixture mix(names);
    mix.print_info();
    using id = IsochoricDerivatives<decltype(mix)>;
    using vd = VirialDerivatives<decltype(mix)>;
    using tdx = TDXDerivatives<decltype(mix)>;
    double T = 300;
    const auto rhovec = (Eigen::ArrayXd(2) << 1.0, 2.0).finished();
    const Eigen::ArrayXd molefrac = (rhovec/rhovec.sum()).eval();
    const double rho = rhovec.sum();
    
    double a00csd = tdx::get_Ar01<ADBackends::complex_step>(mix, T, rho, molefrac);
    double a00cx = tdx::get_Ar01<ADBackends::multicomplex>(mix, T, rho, molefrac);
    double a00ad = tdx::get_Ar01<ADBackends::autodiff>(mix, T, rho, molefrac);
    double a11ad = tdx::get_Ar11<ADBackends::autodiff>(mix, T, rho, molefrac);

    for (auto T = 20; T < 1e5; T *= 1.3) {
        double neff = tdx::get_neff<ADBackends::autodiff>(mix, T, 1e-10, molefrac);
        std::cout << T << "," << neff << std::endl;
    }
    double neff = tdx::get_neff<ADBackends::autodiff>(mix, T, rho, molefrac);
    double a00iso = id::get_Ar01(mix, T, rhovec);
    double apriso = id::get_pr(mix, T, rhovec);
    double B2 = vd::get_B2vir(mix, T, molefrac);
    double B12 = vd::get_B12vir(mix, T, molefrac);

    return EXIT_SUCCESS;
}