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Speed up some PH calls by providing density guesses

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Ian Bell
2016-01-18 00:40:24 -07:00
parent dc9cc4cbd2
commit 8e5930de63
1 changed files with 19 additions and 15 deletions
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34
src/Backends/Helmholtz/FlashRoutines.cpp
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@@ -1286,9 +1286,10 @@ void FlashRoutines::HSU_P_flash_singlephase_Brent(HelmholtzEOSMixtureBackend &HE
CoolPropDbl p, value;
parameters other;
int iter;
CoolPropDbl eos0, eos1;
CoolPropDbl eos0, eos1, rhomolar;
solver_resid(HelmholtzEOSMixtureBackend *HEOS, CoolPropDbl p, CoolPropDbl value, parameters other) :
HEOS(HEOS), p(p), value(value), other(other), iter(0), eos0(-_HUGE), eos1(-_HUGE)
HEOS(HEOS), p(p), value(value), other(other), iter(0), eos0(-_HUGE), eos1(-_HUGE), rhomolar(_HUGE)
{
// Specify the state to avoid saturation calls, but only if phase is subcritical
switch (CoolProp::phases phase = HEOS->phase()) {
@@ -1302,26 +1303,28 @@ void FlashRoutines::HSU_P_flash_singlephase_Brent(HelmholtzEOSMixtureBackend &HE
}
double call(double T){
// Run the solver with T,P as inputs;
HEOS->update(PT_INPUTS, p, T);
if (iter < 3){
// Run the solver with T,P as inputs;
HEOS->update(PT_INPUTS, p, T);
}
else{
// Run the solver with T,P as inputs; but use the guess value for density from before
HEOS->update_TP_guessrho(T, p, rhomolar);
}
// Get the value of the desired variable
CoolPropDbl eos = HEOS->keyed_output(other);
// Store the value of density
rhomolar = HEOS->rhomolar();
// Difference between the two is to be driven to zero
CoolPropDbl r = eos - value;
// Store values for later use if there are errors
if (iter == 0){
eos0 = eos;
}
else if (iter == 1){
eos1 = eos;
}
else{
eos0 = eos1;
eos1 = eos;
}
if (iter == 0){ eos0 = eos; }
else if (iter == 1){ eos1 = eos; }
else{ eos0 = eos1; eos1 = eos; }
iter++;
return r;
@@ -1339,7 +1342,7 @@ void FlashRoutines::HSU_P_flash_singlephase_Brent(HelmholtzEOSMixtureBackend &HE
try{
// First try to use Halley's method (including two derivatives)
Halley(resid, (Tmin+Tmax)/2.0, 1e-12, 100, errstr);
Halley(resid, Tmin, 1e-12, 100, errstr);
if (!is_in_closed_range(Tmin, Tmax, static_cast<CoolPropDbl>(resid.HEOS->T())))
{
throw ValueError("Halley's method was unable to find a solution in HSU_P_flash_singlephase_Brent");
@@ -1349,6 +1352,7 @@ void FlashRoutines::HSU_P_flash_singlephase_Brent(HelmholtzEOSMixtureBackend &HE
}
catch(...){
try{
resid.iter = 0;
// Halley's method failed, so now we try Brent's method
Brent(resid, Tmin, Tmax, DBL_EPSILON, 1e-12, 100, errstr);
// Un-specify the phase of the fluid