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Replacing sqrt(2) with math constant M_SQRT2
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gkogekar committed Sep 4, 2019
1 parent 4e8111d commit b88285d
Showing 1 changed file with 25 additions and 30 deletions.
55 changes: 25 additions & 30 deletions src/thermo/PengRobinsonMFTP.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -10,6 +10,9 @@

#include <boost/math/tools/roots.hpp>

#define _USE_MATH_DEFINES
#include<math.h>

using namespace std;
namespace bmt = boost::math::tools;

Expand Down Expand Up @@ -161,14 +164,13 @@ double PengRobinsonMFTP::cp_mole() const
{
_updateReferenceStateThermo();
double TKelvin = temperature();
double sqt2 = sqrt(2);
double mv = molarVolume();
double vpb = mv + (1 + sqt2)*m_b_current;
double vmb = mv + (1 - sqt2)*m_b_current;
double vpb = mv + (1 + M_SQRT2)*m_b_current;
double vmb = mv + (1 - M_SQRT2)*m_b_current;
pressureDerivatives();
double cpref = GasConstant * mean_X(m_cp0_R);
double dHdT_V = cpref + mv * dpdT_ - GasConstant
+ 1.0 / (2.0 * sqt2 *m_b_current) * log(vpb / vmb) * TKelvin *d2aAlpha_dT2();
+ 1.0 / (2.0 * M_SQRT2 *m_b_current) * log(vpb / vmb) * TKelvin *d2aAlpha_dT2();
return dHdT_V - (mv + TKelvin * dpdT_ / dpdV_) * dpdT_;
}

Expand Down Expand Up @@ -235,9 +237,8 @@ void PengRobinsonMFTP::getActivityCoefficients(double* ac) const
{
double mv = molarVolume();
double T = temperature();
double sqt2 = sqrt(2);
double vpb2 = mv + (1 + sqt2)*m_b_current;
double vmb2 = mv + (1 - sqt2)*m_b_current;
double vpb2 = mv + (1 + M_SQRT2)*m_b_current;
double vmb2 = mv + (1 - M_SQRT2)*m_b_current;
double vmb = mv - m_b_current;
double pres = pressure();

Expand All @@ -249,7 +250,7 @@ void PengRobinsonMFTP::getActivityCoefficients(double* ac) const
}
}
double num = 0;
double den = 2 * sqt2 * m_b_current * m_b_current;
double den = 2 * M_SQRT2 * m_b_current * m_b_current;
double den2 = m_b_current*(mv * mv + 2 * mv * m_b_current - m_b_current * m_b_current);
double RTkelvin = RT();
for (size_t k = 0; k < m_kk; k++) {
Expand Down Expand Up @@ -287,9 +288,8 @@ void PengRobinsonMFTP::getChemPotentials(double* mu) const

double mv = molarVolume();
double vmb = mv - m_b_current;
double sqt2 = sqrt(2);
double vpb2 = mv + (1 + sqt2)*m_b_current;
double vmb2 = mv + (1 - sqt2)*m_b_current;
double vpb2 = mv + (1 + M_SQRT2)*m_b_current;
double vmb2 = mv + (1 - M_SQRT2)*m_b_current;

for (size_t k = 0; k < m_kk; k++) {
m_pp[k] = 0.0;
Expand All @@ -301,7 +301,7 @@ void PengRobinsonMFTP::getChemPotentials(double* mu) const
double pres = pressure();
double refP = refPressure();
double num = 0;
double den = 2 * sqt2 * m_b_current * m_b_current;
double den = 2 * M_SQRT2 * m_b_current * m_b_current;
double den2 = m_b_current*(mv * mv + 2 * mv * m_b_current - m_b_current * m_b_current);

for (size_t k = 0; k < m_kk; k++) {
Expand All @@ -325,11 +325,9 @@ void PengRobinsonMFTP::getPartialMolarEnthalpies(double* hbar) const
// We calculate dpdni_
double TKelvin = temperature();
double mv = molarVolume();
double sqt = sqrt(2);
double vmb = mv - m_b_current;
double sqt2 = sqrt(2);
double vpb2 = mv + (1 + sqt2)*m_b_current;
double vmb2 = mv + (1 - sqt2)*m_b_current;
double vpb2 = mv + (1 + M_SQRT2)*m_b_current;
double vmb2 = mv + (1 - M_SQRT2)*m_b_current;

for (size_t k = 0; k < m_kk; k++) {
m_pp[k] = 0.0;
Expand All @@ -352,7 +350,7 @@ void PengRobinsonMFTP::getPartialMolarEnthalpies(double* hbar) const

pressureDerivatives();
double fac2 = mv + TKelvin * dpdT_ / dpdV_;
double fac3 = 2 * sqt * m_b_current *m_b_current;
double fac3 = 2 * M_SQRT2 * m_b_current *m_b_current;
for (size_t k = 0; k < m_kk; k++) {
double hE_v = mv * dpdni_[k] - RTkelvin + (2 * m_b_current - b_vec_Curr_[k]) / fac3 * log(vpb2 / vmb2)*fac
+ (mv * b_vec_Curr_[k]) /(m_b_current*den) * fac;
Expand All @@ -367,14 +365,13 @@ void PengRobinsonMFTP::getPartialMolarEntropies(double* sbar) const
scale(sbar, sbar+m_kk, sbar, GasConstant);
double TKelvin = temperature();
double mv = molarVolume();
double sqt2 = sqrt(2);
double vmb = mv - m_b_current;
double vpb2 = mv + (1 + sqt2)*m_b_current;
double vmb2 = mv + (1 - sqt2)*m_b_current;
double vpb2 = mv + (1 + M_SQRT2)*m_b_current;
double vmb2 = mv + (1 - M_SQRT2)*m_b_current;
double refP = refPressure();
double daAlphadT = daAlpha_dT();
double coeff1 = 0;
double den1 = 2 * sqt2 * m_b_current * m_b_current;
double den1 = 2 * M_SQRT2 * m_b_current * m_b_current;
double den2 = mv * mv + 2 * mv * m_b_current - m_b_current * m_b_current;

// Calculate sum(n_j (a alpha)_i, k * (1/alpha_k d/dT(alpha_k))) -> m_pp
Expand Down Expand Up @@ -600,7 +597,7 @@ vector<double> PengRobinsonMFTP::getCoeff(const std::string& iName)
}

//Assuming no temperature dependence
spCoeff[0] = omega_a * pow(GasConstant, 2) * pow(T_crit, 2) / P_crit; //coeff a
spCoeff[0] = omega_a * (GasConstant* GasConstant) * (T_crit* T_crit) / P_crit; //coeff a
spCoeff[1] = omega_b * GasConstant * T_crit / P_crit; // coeff b
break;
}
Expand Down Expand Up @@ -772,10 +769,9 @@ double PengRobinsonMFTP::sresid() const
double zz = z();
double alpha_1 = daAlpha_dT();
double T = temperature();
double sqt2 = sqrt(2.0);
double vpb = molarV + (1.0 + sqt2) *m_b_current;
double vmb = molarV + (1.0 - sqt2) *m_b_current;
double fac = alpha_1 / (2.0 * sqt2 * m_b_current);
double vpb = molarV + (1.0 + M_SQRT2) *m_b_current;
double vmb = molarV + (1.0 - M_SQRT2) *m_b_current;
double fac = alpha_1 / (2.0 * M_SQRT2 * m_b_current);
double sresid_mol_R = log(zz*(1.0 - hh)) + fac * log(vpb / vmb) / GasConstant;
return GasConstant * sresid_mol_R;
}
Expand All @@ -786,10 +782,9 @@ double PengRobinsonMFTP::hresid() const
double zz = z();
double aAlpha_1 = daAlpha_dT();
double T = temperature();
double sqt2 = sqrt(2);
double vpb = molarV + (1 + sqt2) *m_b_current;
double vmb = molarV + (1 - sqt2) *m_b_current;
double fac = 1 / (2.0 * sqt2 * m_b_current);
double vpb = molarV + (1 + M_SQRT2) *m_b_current;
double vmb = molarV + (1 - M_SQRT2) *m_b_current;
double fac = 1 / (2.0 * M_SQRT2 * m_b_current);
return GasConstant * T * (zz - 1.0) + fac * log(vpb / vmb) *(T * aAlpha_1 - m_aAlpha_current);
}

Expand Down

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