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March 23, 2017, 05:11 
phasefraction equation in multiphase model

#1 
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zhengzongji
Join Date: Feb 2017
Posts: 9
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hi, Dear foamers
I have just learned phasefraction equation in twophase model It is ez to understand: ∂(alpha)+∇·(U·alpha) = 0 but when it turns to multiphase model, I can hardly figure out what the equation will change into. Could anybody gives me some suggestions or gives some links related to this? thanks zzj 

March 23, 2017, 12:41 

#2 
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Declan
Join Date: Oct 2016
Location: Ireland
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I think it is the same for each of the i phases:
∂(alpha_i)+∇·(U·alpha_i) = 0 

March 24, 2017, 05:00 

#3  
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Ricky
Join Date: Jul 2014
Location: Germany
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Quote:
__________________
If it is easy, then something is fishy! 

March 27, 2017, 02:17 

#4  
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zhengzongji
Join Date: Feb 2017
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Quote:
Dear decah，thanks for your replying. In fact,the code shows that in multiphase mixture model we need to solve a variable named "alphaPhiCorr". but "alphaPhiCorr" need all the phases to solve. (It means we can not solve fraction equation phase by phase) And the fraction equation is: ∂(alpha)+∇·(alphaPhiCorr) = 0.(I get the equation from multiphaseMixture.c) MULES::limit ( 1.0/mesh_.time().deltaT().value(), geometricOneField(), alpha, phi_, alphaPhiCorr, zeroField(), zeroField(), 1, 0, true ); And alphaPhiCorr is solved by each phase,following is the code: alphaPhiCorrs.set ( phasei, new surfaceScalarField ( "phi" + alpha.name() + "Corr", fvc::flux ( phi_, alpha, alphaScheme ) ) ); surfaceScalarField& alphaPhiCorr = alphaPhiCorrs[phasei]; forAllIter(PtrDictionary<phase>, phases_, iter2) { phase& alpha2 = iter2(); if (&alpha2 == &alpha) continue; surfaceScalarField phir(phic*nHatf(alpha, alpha2)); alphaPhiCorr += fvc::flux ( fvc::flux(phir, alpha2, alpharScheme), alpha, alpharScheme ); } I do not know what does the alphaPhiCorr mean. May be a mathematical formula can help easier understanding. Last edited by zzj; March 27, 2017 at 03:22. 

March 27, 2017, 02:22 

#5 
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zhengzongji
Join Date: Feb 2017
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Dear kera,thanks for your help.
I am reading the essay. I will reply after reading. thanks again. 

March 27, 2017, 03:18 

#6  
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zhengzongji
Join Date: Feb 2017
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Quote:
I have finished reading. Unfortunately,The paper only gives the equation of two phases model, I can hardly figure out the equation in multiphase model. 

April 5, 2017, 04:33 

#7 
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zhengzongji
Join Date: Feb 2017
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Finally,I figure out the equations
In fact, Decah's idea is right, we just need to solve each phase. 

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