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[Thermo] Fix setting of temperature-dependent Redlich-Kwong parameters

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Using negative values to indicate unspecified parameters doesn't work, since
either constant in "a = a0 + a1*T" can be negative and still produce a positive
value for "a". Instead, NaN can be used for this purpose.
This commit is contained in:
Ray Speth 2019-02-04 12:11:57 -05:00
parent 3ff5d87b81
commit ebb93cb5a2
3 changed files with 15 additions and 13 deletions
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1
include/cantera/base/ct_defs.h
View file

@ -35,6 +35,7 @@ namespace Cantera
using std::shared_ptr;
using std::make_shared;
using std::isnan; // workaround for bug in libstdc++ 4.8
/*!
* All physical constants are stored here.

22
src/thermo/RedlichKwongMFTP.cpp
View file

@ -80,12 +80,11 @@ void RedlichKwongMFTP::setSpeciesCoeffs(const std::string& species,
continue;
}
// a_coeff_vec is initialized to -1, so screen for unidentified species to prevent
// imaginary numbers on the off-diagonals:
if (a_coeff_vec(0, j + m_kk * j) < 0 || a_coeff_vec(1, j + m_kk * j) < 0){
// a_coeff_vec(0) is initialized to NaN to mark uninitialized species
if (isnan(a_coeff_vec(0, j + m_kk * j))) {
// The diagonal element of the jth species has not yet been defined.
continue;
} else if (a_coeff_vec(0, j + m_kk * k) == -1) {
} else if (isnan(a_coeff_vec(0, j + m_kk * k))) {
// Only use the mixing rules if the off-diagonal element has not already been defined by a
// user-specified crossFluidParameters entry:
double a0kj = sqrt(a_coeff_vec(0, j + m_kk * j) * a0);
@ -555,10 +554,10 @@ bool RedlichKwongMFTP::addSpecies(shared_ptr<Species> spec)
if (added) {
a_vec_Curr_.resize(m_kk * m_kk, 0.0);
// Initialize a_vec and b_vec to -1, to screen for species with
// Initialize a_vec and b_vec to NaN, to screen for species with
// pureFluidParameters which are undefined in the input file:
b_vec_Curr_.push_back(-1);
a_coeff_vec.resize(2, m_kk * m_kk, -1);
b_vec_Curr_.push_back(NAN);
a_coeff_vec.resize(2, m_kk * m_kk, NAN);
m_pp.push_back(0.0);
m_tmpV.push_back(0.0);
@ -614,8 +613,7 @@ void RedlichKwongMFTP::initThermoXML(XML_Node& phaseNode, const std::string& id)
size_t counter = iSpecies + m_kk * iSpecies;
// If not, then search the database:
if (a_coeff_vec(0, counter) == -1 ||
b_vec_Curr_[iSpecies] == -1) {
if (isnan(a_coeff_vec(0, counter))) {
vector<double> coeffArray;
@ -626,7 +624,7 @@ void RedlichKwongMFTP::initThermoXML(XML_Node& phaseNode, const std::string& id)
// Check if species was found in the database of critical properties,
// and assign the results
if (coeffArray[0] != -1 || coeffArray[1] != -1) {
if (!isnan(coeffArray[0])) {
//Assuming no temperature dependence (i,e a1 = 0)
setSpeciesCoeffs(iName, coeffArray[0], 0.0, coeffArray[1]);
}
@ -651,9 +649,7 @@ vector<double> RedlichKwongMFTP::getCoeff(const std::string& iName)
{
vector_fp vParams;
bool found = false;
vector<double> spCoeff(2);
spCoeff[0] = -1;
spCoeff[1] = -1;
vector_fp spCoeff{NAN, NAN};
// Get number of species in the database
// open xml file critProperties.xml

5
test/thermo/phaseConstructors.cpp
View file

@ -323,6 +323,11 @@ TEST_F(ConstructFromScratch, RedlichKwongMFTP)
// Arbitrary regression test values
EXPECT_NEAR(p.density(), 892.421, 2e-3);
EXPECT_NEAR(p.enthalpy_mole(), -404848642.3797, 1e-3);
p.setMoleFractionsByName("CO2:.6, H2O:0.02, H2:0.38");
p.setState_TP(350, 180*OneAtm);
EXPECT_NEAR(p.density(), 181.568, 2e-3);
EXPECT_NEAR(p.gibbs_mass(), -1.0607e7, 2e3);
}
TEST_F(ConstructFromScratch, IdealSolnGasVPSS_gas)