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Water viscosity can now be evaluated at the critical point

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Signed-off-by: Ian Bell <ian.h.bell@gmail.com>
This commit is contained in:
Ian Bell
2014-06-03 17:49:23 +02:00
parent a069e68720
commit 331690de8c
1 changed files with 12 additions and 2 deletions
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14
src/Helmholtz.cpp
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@@ -1032,6 +1032,7 @@ long double ResidualHelmholtzNonAnalytic::dTau(const long double &tau, const lon
long double ResidualHelmholtzNonAnalytic::dDelta2(const long double &tau, const long double &delta) throw()
{
long double dDELTA2_dDelta2, dDELTAbi2_dDelta2;
if (N==0){return 0.0;}
for (unsigned int i=0; i<N; ++i)
{
@@ -1045,9 +1046,18 @@ long double ResidualHelmholtzNonAnalytic::dDelta2(const long double &tau, const
long double dPSI_dDelta=-2.0*Ci*(delta-1.0)*PSI;
long double dDELTA_dDelta=(delta-1.0)*(Ai*theta*2.0/betai*pow(pow(delta-1.0,2),1.0/(2.0*betai)-1.0)+2.0*Bi*ai*pow(pow(delta-1.0,2),ai-1.0));
long double dDELTA_dDelta_over_delta_minus_1=(Ai*theta*2.0/betai*pow(pow(delta-1.0,2),1.0/(2.0*betai)-1.0)+2.0*Bi*ai*pow(pow(delta-1.0,2),ai-1.0));
long double dPSI2_dDelta2=(2.0*Ci*pow(delta-1.0,2)-1.0)*2.0*Ci*PSI;
long double dDELTA2_dDelta2=1.0/(delta-1.0)*dDELTA_dDelta+pow(delta-1.0,2)*(4.0*Bi*ai*(ai-1.0)*pow(pow(delta-1.0,2),ai-2.0)+2.0*pow(Ai/betai,2)*pow(pow(pow(delta-1.0,2),1.0/(2.0*betai)-1.0),2)+Ai*theta*4.0/betai*(1.0/(2.0*betai)-1.0)*pow(pow(delta-1.0,2),1.0/(2.0*betai)-2.0));
long double dDELTAbi2_dDelta2=bi*(pow(DELTA,bi-1.0)*dDELTA2_dDelta2+(bi-1.0)*pow(DELTA,bi-2.0)*pow(dDELTA_dDelta,2));
if (fabs(delta-1) < 10*DBL_EPSILON){
dDELTA2_dDelta2 = 0;
dDELTAbi2_dDelta2 = 0;
}
else{
dDELTA2_dDelta2 = dDELTA_dDelta_over_delta_minus_1+pow(delta-1.0,2)*(4.0*Bi*ai*(ai-1.0)*pow(pow(delta-1,2),ai-2.0)+2.0*pow(Ai/betai,2)*pow(pow(pow(delta-1,2),1.0/(2.0*betai)-1.0),2)+Ai*theta*4.0/betai*(1.0/(2.0*betai)-1.0)*pow(pow(delta-1.0,2),1.0/(2.0*betai)-2.0));
dDELTAbi2_dDelta2 = bi*(pow(DELTA,bi-1.0)*dDELTA2_dDelta2+(bi-1.0)*pow(DELTA,bi-2.0)*pow(dDELTA_dDelta,2));
}
// At critical point, DELTA is 0, and 1/0^n is undefined
if (fabs(DELTA) < 10*DBL_EPSILON)