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Added a bunch of mixture derivative tests (all passing).

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Signed-off-by: Ian Bell <ian.h.bell@gmail.com>
This commit is contained in:
Ian Bell
2014-08-26 21:00:45 +02:00
parent 28eb696660
commit 5316a1fd93
1 changed files with 132 additions and 2 deletions
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134
src/Backends/Helmholtz/MixtureDerivatives.cpp
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@@ -210,7 +210,6 @@ long double MixtureDerivatives::d_ndalphardni_dDelta(HelmholtzEOSMixtureBackend
}
return term1 + term2 + term3;
}
long double MixtureDerivatives::d_ndalphardni_dTau(HelmholtzEOSMixtureBackend &HEOS, std::size_t i)
{
// The first line
@@ -228,5 +227,136 @@ long double MixtureDerivatives::d_ndalphardni_dTau(HelmholtzEOSMixtureBackend &H
return term1 + term2 + term3;
}
} /* namespace CoolProp */
#ifdef ENABLE_CATCH
#include "catch.hpp"
using namespace CoolProp;
TEST_CASE("Mixture derivative checks", "[mixtures],[mixture_derivs]")
{
/* Set up a test class for the mixture tests */
std::vector<std::string> names(2);
names[0] = "Methane"; names[1] = "Ethane";
std::vector<long double> z(2);
z[0] = 0.5; z[1] = 1-z[0];
shared_ptr<HelmholtzEOSMixtureBackend> HEOS(new HelmholtzEOSMixtureBackend(names));
HelmholtzEOSMixtureBackend &rHEOS = *(HEOS.get());
rHEOS.set_mole_fractions(z);
// These ones only require the i index
for (std::size_t i = 0; i< z.size();++i)
{
std::ostringstream ss1;
ss1 << "dln_fugacity_coefficient_dT__constp_n, i=" << i;
SECTION(ss1.str(), "")
{
double T1 = 300, dT = 1e-3;
rHEOS.specify_phase(iphase_gas);
rHEOS.update(PT_INPUTS, 101325, T1);
double analytic = MixtureDerivatives::dln_fugacity_coefficient_dT__constp_n(rHEOS, i);
rHEOS.update(PT_INPUTS, 101325, T1 + dT);
double v1 = MixtureDerivatives::ln_fugacity_coefficient(rHEOS, i);
rHEOS.update(PT_INPUTS, 101325, T1 - dT);
double v2 = MixtureDerivatives::ln_fugacity_coefficient(rHEOS, i);
double numeric = (v1 - v2)/(2*dT);
double err = std::abs((numeric-analytic)/analytic);
CHECK(err < 1e-6);
}
std::ostringstream ss2;
ss2 << "dln_fugacity_coefficient_dp__constT_n, i=" << i;
SECTION(ss2.str(), "")
{
double p1 = 101325, dP = 1;
rHEOS.specify_phase(iphase_gas);
rHEOS.update(PT_INPUTS, p1, 300);
double analytic = MixtureDerivatives::dln_fugacity_coefficient_dp__constT_n(rHEOS, i);
rHEOS.update(PT_INPUTS, p1 + dP, 300);
double v1 = MixtureDerivatives::ln_fugacity_coefficient(rHEOS, i);
rHEOS.update(PT_INPUTS, p1 - dP, 300);
double v2 = MixtureDerivatives::ln_fugacity_coefficient(rHEOS, i);
double numeric = (v1 - v2)/(2*dP);
double err = std::abs((numeric-analytic)/analytic);
CHECK(err < 1e-6);
}
std::ostringstream ss3;
ss3 << "d_ndalphardni_dDelta, i=" << i;
SECTION(ss3.str(), "")
{
double p1 = 101325, dP = 1e-1;
rHEOS.specify_phase(iphase_gas);
rHEOS.update(PT_INPUTS, p1, 300);
double analytic = MixtureDerivatives::d_ndalphardni_dDelta(rHEOS, i);
rHEOS.update(PT_INPUTS, p1 + dP, 300);
double v1 = MixtureDerivatives::ndalphar_dni__constT_V_nj(rHEOS, i), delta1 = rHEOS.delta();
rHEOS.update(PT_INPUTS, p1 - dP, 300);
double v2 = MixtureDerivatives::ndalphar_dni__constT_V_nj(rHEOS, i), delta2 = rHEOS.delta();
double numeric = (v1 - v2)/(delta1 - delta2);
double err = std::abs((numeric-analytic)/analytic);
CHECK(err < 1e-6);
}
std::ostringstream ss4;
ss4 << "d_ndalphardni_dTau, i=" << i;
SECTION(ss4.str(), "")
{
double p1 = 101325, dT = 1e-2;
rHEOS.specify_phase(iphase_gas);
rHEOS.update(PT_INPUTS, 101325, 300);
double rho1 = rHEOS.rhomolar();
rHEOS.update(DmolarT_INPUTS, rho1, 300);
double analytic = MixtureDerivatives::d_ndalphardni_dTau(rHEOS, i);
rHEOS.update(DmolarT_INPUTS, rho1, 300 + dT);
double v1 = MixtureDerivatives::ndalphar_dni__constT_V_nj(rHEOS, i), tau1 = rHEOS.tau();
rHEOS.update(DmolarT_INPUTS, rho1, 300 - dT);
double v2 = MixtureDerivatives::ndalphar_dni__constT_V_nj(rHEOS, i), tau2 = rHEOS.tau();
double numeric = (v1 - v2)/(tau1 - tau2);
double err = std::abs((numeric-analytic)/analytic);
CHECK(err < 1e-6);
}
// These derivatives depend on both the i and j indices
for (std::size_t j = 0; j < z.size(); ++j){
std::ostringstream ss1;
ss1 << "dln_fugacity_coefficient_dxj__constT_p_xi, i=" << i << ", j=" << j;
SECTION(ss1.str(), "")
{
double dz = 1e-6;
rHEOS.specify_phase(iphase_gas);
rHEOS.update(PT_INPUTS, 101325, 300);
double rho1 = rHEOS.rhomolar();
double analytic = MixtureDerivatives::dln_fugacity_coefficient_dxj__constT_p_xi(rHEOS, i, j);
std::vector<long double> zp = z; /// Copy base composition
zp[j] += dz;
rHEOS.set_mole_fractions(zp);
rHEOS.update(PT_INPUTS, 101325, 300);
double v1 = MixtureDerivatives::ln_fugacity_coefficient(rHEOS, i), tau1 = rHEOS.tau();
std::vector<long double> zm = z; /// Copy base composition
zm[j] -= dz;
rHEOS.set_mole_fractions(zm);
rHEOS.update(PT_INPUTS, 101325, 300);
double v2 = MixtureDerivatives::ln_fugacity_coefficient(rHEOS, i), tau2 = rHEOS.tau();
double numeric = (v1 - v2)/(2*dz);
double err = std::abs((numeric-analytic)/analytic);
CHECK(err < 1e-6);
}
}
}
}
#endif