research/cantera
1
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions

[Thermo] Convert Shomate coefficients when creating objects

Browse source 
Do conversion to nondimensional units once when creating the ShomatePoly object,
instead of every time that properties are calculated.
This commit is contained in:
Ray Speth 2015-07-17 18:18:03 -04:00
parent 761f54f241
commit b7a5aff900
2 changed files with 52 additions and 53 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

78
include/cantera/thermo/ShomatePoly.h
View file

@ -72,8 +72,11 @@ public:
*/
ShomatePoly(double tlow, double thigh, double pref, const double* coeffs) :
SpeciesThermoInterpType(tlow, thigh, pref),
m_coeff(coeffs, coeffs + 7)
m_coeff(7)
{
for (size_t i = 0; i < 7; i++) {
m_coeff[i] = coeffs[i] * 1000 / GasConstant;
}
}
virtual SpeciesThermoInterpType*
@ -85,7 +88,7 @@ public:
return SHOMATE;
}
virtual size_t temperaturePolySize() const { return 7; }
virtual size_t temperaturePolySize() const { return 6; }
virtual void updateTemperaturePoly(double T, double* T_poly) const {
doublereal tt = 1.e-3*T;
@ -94,8 +97,7 @@ public:
T_poly[2] = T_poly[1] * tt;
T_poly[3] = 1.0/T_poly[1];
T_poly[4] = std::log(tt);
T_poly[5] = 1.0/GasConstant;
T_poly[6] = 1.0/(GasConstant * T);
T_poly[5] = 1.0/tt;
}
//! Update the properties for this species, given a temperature polynomial
@ -105,14 +107,13 @@ public:
* pointers to arrays where the computed property values should be
* written. This method updates only one value in each array.
*
* - `tt` is T/1000.
* - `m_t[0] = tt`
* - `m_t[1] = tt*tt`
* - `m_t[2] = m_t[1]*tt`
* - `m_t[3] = 1.0/m_t[1]`
* - `m_t[4] = log(tt)`
* - `m_t[5] = 1.0/GasConstant`
* - `m_t[6] = 1.0/(GasConstant * T)`
* - `t` is T/1000.
* - `t[0] = t`
* - `t[1] = t*t`
* - `t[2] = t[1]*t`
* - `t[3] = 1.0/t[1]`
* - `t[4] = log(t)`
* - `t[5] = 1.0/t;
*
* @param tt Vector of temperature polynomials
* @param cp_R Vector of Dimensionless heat capacities. (length m_kk).
@ -128,32 +129,18 @@ public:
doublereal Ct2 = m_coeff[2]*tt[1];
doublereal Dt3 = m_coeff[3]*tt[2];
doublereal Etm2 = m_coeff[4]*tt[3];
doublereal F = m_coeff[5];
doublereal Ftm1 = m_coeff[5]*tt[5];
doublereal G = m_coeff[6];
doublereal cp, h, s;
cp = A + Bt + Ct2 + Dt3 + Etm2;
h = tt[0]*(A + 0.5*Bt + 1.0/3.0*Ct2 + 0.25*Dt3 - Etm2) + F;
s = A*tt[4] + Bt + 0.5*Ct2 + 1.0/3.0*Dt3 - 0.5*Etm2 + G;
/*
* Shomate polynomials parameterizes assuming units of
* J/(gmol*K) for cp_r and s_R and kJ/(gmol) for h.
* However, Cantera assumes default MKS units of
* J/(kmol*K). This requires us to multiply cp and s
* by 1.e3 and h by 1.e6, before we then nondimensionalize
* the results by dividing by (GasConstant * T),
* where GasConstant has units of J/(kmol * K).
*/
*cp_R = 1.e3 * cp * tt[5];
*h_RT = 1.e6 * h * tt[6];
*s_R = 1.e3 * s * tt[5];
*cp_R = A + Bt + Ct2 + Dt3 + Etm2;
*h_RT = A + 0.5*Bt + 1.0/3.0*Ct2 + 0.25*Dt3 - Etm2 + Ftm1;
*s_R = A*tt[4] + Bt + 0.5*Ct2 + 1.0/3.0*Dt3 - 0.5*Etm2 + G;
}
virtual void updatePropertiesTemp(const doublereal temp,
doublereal* cp_R, doublereal* h_RT,
doublereal* s_R) const {
double tPoly[7];
double tPoly[6];
updateTemperaturePoly(temp, tPoly);
updateProperties(tPoly, cp_R, h_RT, s_R);
}
@ -168,7 +155,7 @@ public:
thigh = m_highT;
pref = m_Pref;
for (int i = 0; i < 7; i++) {
coeffs[i] = m_coeff[i];
coeffs[i] = m_coeff[i] * GasConstant / 1000;
}
}
@ -178,36 +165,21 @@ public:
* parameters for the standard state.
*/
virtual void modifyParameters(doublereal* coeffs) {
if (m_coeff.size() != 7) {
throw CanteraError("modifyParameters",
"modifying something that hasn't been initialized");
for (size_t i = 0; i < 7; i++) {
m_coeff[i] = coeffs[i] * 1000 / GasConstant;
}
std::copy(coeffs, coeffs + 7, m_coeff.begin());
}
virtual doublereal reportHf298(doublereal* const h298 = 0) const {
double tPoly[7];
updateTemperaturePoly(298.15, tPoly);
doublereal A = m_coeff[0];
doublereal Bt = m_coeff[1]*tPoly[0];
doublereal Ct2 = m_coeff[2]*tPoly[1];
doublereal Dt3 = m_coeff[3]*tPoly[2];
doublereal Etm2 = m_coeff[4]*tPoly[3];
doublereal F = m_coeff[5];
doublereal h = tPoly[0]*(A + 0.5*Bt + 1.0/3.0*Ct2 + 0.25*Dt3 - Etm2) + F;
double hh = 1.e6 * h;
if (h298) {
*h298 = 1.e6 * h;
}
return hh;
double cp_R, h_RT, s_R;
updatePropertiesTemp(298.15, &cp_R, &h_RT, &s_R);
return h_RT * GasConstant * 298.15;
}
virtual void modifyOneHf298(const size_t k, const doublereal Hf298New) {
doublereal hnow = reportHf298();
doublereal delH = Hf298New - hnow;
m_coeff[5] += delH / 1.0E6;
m_coeff[5] += delH / (1e3 * GasConstant);
}
protected:

27
test/thermo/thermoParameterizations.cpp
View file

@ -103,3 +103,30 @@ TEST_F(SpeciesThermoInterpTypeTest, install_shomate)
EXPECT_DOUBLE_EQ(p2.entropy_mass(), p.entropy_mass());
EXPECT_DOUBLE_EQ(p2.cp_mass(), p.cp_mass());
}
TEST(Shomate, modifyParameters)
{
ShomatePoly2 S1(200, 6000, 101325, co2_shomate_coeffs);
ShomatePoly2 S2(200, 6000, 101325, co_shomate_coeffs);
S2.modifyParameters((double*) co2_shomate_coeffs);
double cp1, cp2, h1, h2, s1, s2;
S1.updatePropertiesTemp(500, &cp1, &h1, &s1);
S2.updatePropertiesTemp(500, &cp2, &h2, &s2);
EXPECT_DOUBLE_EQ(cp1, cp2);
EXPECT_DOUBLE_EQ(h1, h2);
EXPECT_DOUBLE_EQ(s1, s2);
}
TEST(Shomate, modifyOneHf298)
{
ShomatePoly2 S(200, 6000, 101325, co2_shomate_coeffs);
EXPECT_NEAR(-393.5224e6, S.reportHf298(), 1e4);
double Htest = -400e6;
S.modifyOneHf298(npos, Htest);
double cp, h, s;
S.updatePropertiesTemp(298.15, &cp, &h, &s);
EXPECT_DOUBLE_EQ(Htest, h * 298.15 * GasConstant);
EXPECT_DOUBLE_EQ(Htest, S.reportHf298());
}