interPhaseChangeFoam: sqrt(negativeValue) in SchnerrSauer

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 November 16, 2010, 11:03 interPhaseChangeFoam: sqrt(negativeValue) in SchnerrSauer #1 Member   David Hora Join Date: Mar 2009 Location: Zürich, Switzerland Posts: 63 Rep Power: 10 Hi everybody A negative saturation pressure can cause a floating point exception in the following function: Foam:haseChangeTwoPhaseMixtures::SchnerrSauer: Coeff ( const volScalarField& p ) const { volScalarField limitedAlpha1 = min(max(alpha1_, scalar(0)), scalar(1)); volScalarField rho = (limitedAlpha1*rho1() + (scalar(1) - limitedAlpha1)*rho2()); return (3*rho1()*rho2())*sqrt(2/(3*rho1())) *rRb(limitedAlpha1)/(rho*sqrt(mag(p - pSat()) + 0.01*pSat())); } The problem occured in 'sqrt(mag(p - pSat()) + 0.01*pSat())' when I tried to reduce the saturation pressure stepwise from an initial solution without cavitation. I know that a simple solution would be to use a higher pressure level but that's not really satisfying in my opininion. Does anybody know more about the term 0.01*pSat? I found some papers (not the referenced one) but this term is never mentioned. Regards David

 November 17, 2010, 04:51 #2 Member   David Hora Join Date: Mar 2009 Location: Zürich, Switzerland Posts: 63 Rep Power: 10 I use return (3*rho1()*rho2())*sqrt(2/(3*rho1())) *rRb(limitedAlpha1)/(rho*sqrt(max(mag(p - pSat()),dimensionedScalar("p",dimensionSet(1,-1,-2,0,0,0,0),VSMALL)))); as intermediate solution. Any comment is very appreciated. Regards David

February 20, 2014, 08:57
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Baris (Heewa)
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Quote:
 Originally Posted by david I use return (3*rho1()*rho2())*sqrt(2/(3*rho1())) *rRb(limitedAlpha1)/(rho*sqrt(max(mag(p - pSat()),dimensionedScalar("p",dimensionSet(1,-1,-2,0,0,0,0),VSMALL)))); as intermediate solution. Any comment is very appreciated. Regards David
Hi Dear David,

Maybe it is a bit late but for few months i started to interested indeed with openfoam and try to make cavitation simulation in nozzle by using interphasechangeFoam. I have faced same problem too. Could you tell me that what is the meaning of mag(p - pSat()) + 0.01*pSat()) ???

i hope that you already got answer about it and your help will be very appreciated.

Best Regards...

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