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Catch singular explosions in saturation_PHSU_pure #2250

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merged 6 commits into from
Jan 16, 2024
Merged

Catch singular explosions in saturation_PHSU_pure #2250

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41739c5
Catch singular explosions in saturation_PHSU_pure
msaitta-mpr May 10, 2023
c1dc498
Add comment to explain error check in saturation_PHSU_pure
msaitta-mpr May 12, 2023
f249f3f
Add extra update check after saturation_PHSU_pure
msaitta-mpr May 26, 2023
c6b650b
Ensure that saturated phase is specified
msaitta-mpr May 26, 2023
1331b4d
Revert "Ensure that saturated phase is specified"
msaitta-mpr Sep 22, 2023
475e5b3
Update the ammonio saturated rhoV ancillary
msaitta-mpr Sep 22, 2023
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34 changes: 21 additions & 13 deletions dev/fluids/Ammonia.json
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Original file line number Diff line number Diff line change
Expand Up @@ -99,23 +99,31 @@
"Tmax": 405.56,
"Tmin": 195.495,
"description": "rho'' = rhoc*exp(Tc/T*sum(n_i*theta^t_i))",
"max_abserror_percentage": 0.802513430755436,
"max_abserror_percentage": 0.312705,
"n": [
-0.053296,
-3.4589,
-6.7572,
-17.26,
-43.12,
-115.18
0.0,
-3.6322306612603197,
43.53295636848281,
-396.7025942753399,
1946.6788208368914,
-5739.851852849688,
10341.987533476391,
-11168.484405912883,
6642.700525911098,
-1675.050456540271
],
"reducing_value": 13696,
"t": [
0.14,
0.44,
1.314,
3.225,
6.4,
14.0
0.0,
0.3333333333333333,
0.5,
0.6666666666666666,
0.8333333333333334,
1.0,
1.1666666666666667,
1.3333333333333333,
1.5,
1.6666666666666667
],
"type": "rhoV",
"using_tau_r": true
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46 changes: 46 additions & 0 deletions src/Backends/Helmholtz/VLERoutines.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -554,6 +554,52 @@ void SaturationSolvers::saturation_PHSU_pure(HelmholtzEOSMixtureBackend& HEOS, C
info.c_str(), specified_value, error));
}
} while (error > 1e-9);
// Recalculate error
// The result has changed since the last error calculation.
// In rare scenarios, the final step can become unstable due to solving a singular
// J matrix. This final error check verifies that the solution is still good.
// Furthermore, the forced phase of SatL and SatV may have caused errors. We will recalculate them without this assumption.
Comment on lines +557 to +561
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@danielkwalsh danielkwalsh Jan 6, 2024 •
edited
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Does the singular J matrix still crop up with the fixed ancillary? I'm wondering if this part of the code is still needed?

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I never actually checked whether it is still needed. I figure that it is a cheap enough check that it is probably worth leaving in.

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Okay, great. I'm satisfied with that.

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@msaitta-mpr @ibell, so what are the next steps to get this merged?

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If everyone agrees we are ready I can merge it

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I believe that in its current state that it fixes the known issue and does not introduce any others. It raises the question of whether there are other ancillary issues hidden elsewhere, but I think that we should merge for now and reevaluate the ancillaries some other time.

SatL->unspecify_phase();
SatV->unspecify_phase();
SatL->update(DmolarT_INPUTS, rhoL, T);
SatV->update(DmolarT_INPUTS, rhoV, T);
negativer[0] = -(deltaV * (1 + deltaV * SatV->dalphar_dDelta()) - deltaL * (1 + deltaL * SatL->dalphar_dDelta()));
negativer[1] = -(deltaV * SatV->dalphar_dDelta() + SatV->alphar() + log(deltaV) - deltaL * SatL->dalphar_dDelta() - SatL->alphar() - log(deltaL));
switch (options.specified_variable) {
case saturation_PHSU_pure_options::IMPOSED_PL:
// -r_3 (equate calculated pressure and specified liquid pressure)
negativer[2] = -(SatL->p() / specified_value - 1);
break;
case saturation_PHSU_pure_options::IMPOSED_PV:
// -r_3 (equate calculated pressure and specified vapor pressure)
negativer[2] = -(SatV->p() / specified_value - 1);
break;
case saturation_PHSU_pure_options::IMPOSED_HL:
// -r_3 (equate calculated liquid enthalpy and specified liquid enthalpy)
negativer[2] = -(SatL->hmolar() - specified_value);
break;
case saturation_PHSU_pure_options::IMPOSED_HV:
// -r_3 (equate calculated vapor enthalpy and specified vapor enthalpy)
negativer[2] = -(SatV->hmolar() - specified_value);
break;
case saturation_PHSU_pure_options::IMPOSED_SL:
// -r_3 (equate calculated liquid entropy and specified liquid entropy)
negativer[2] = -(SatL->smolar() - specified_value);
break;
case saturation_PHSU_pure_options::IMPOSED_SV:
// -r_3 (equate calculated vapor entropy and specified vapor entropy)
negativer[2] = -(SatV->smolar() - specified_value);
break;
default:
throw ValueError(format("options.specified_variable to saturation_PHSU_pure [%d] is invalid", options.specified_variable));
}
error = sqrt(pow(negativer[0], 2) + pow(negativer[1], 2) + pow(negativer[2], 2));
// reset the phase for the next update.
SatL->specify_phase(iphase_liquid);
SatV->specify_phase(iphase_gas);
if (error > 1e-8){
throw SolutionError(format("saturation_PHSU_pure solver was good, but went bad. Current error is %Lg", error));
}
}
void SaturationSolvers::saturation_D_pure(HelmholtzEOSMixtureBackend& HEOS, CoolPropDbl rhomolar, saturation_D_pure_options& options)
{
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