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October 6, 2010, 15:43 

#2 
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Santiago Marquez Damian
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Hmm, I think actually only variation of viscosity by volume fraction is taken into account, not by nonlinear viscosity laws. But it could be implemented.
Best.
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Santiago MÁRQUEZ DAMIÁN, Ph.D. Postdoctoral Fellow Research Center for Computational Mechanics (CIMEC)  CONICET/FICHUNL T.E.: 543424511594 Ext. 1005 Güemes 3450  (3000) Santa Fe Santa Fe  Argentina http://www.cimec.org.ar 

October 8, 2010, 20:03 

#4 
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Santiago Marquez Damian
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Nima, in UEqn.H there some lines defining the momentum equation for interFoam, basically it has same terms of usual NS equations for newtonian incompressible fluid plus the term due spatial variation of viscosity
fvc::grad(U) & fvc::grad(muEff) and term due surface tension fvc::interpolate(interface.sigmaK())*fvc::snGrad(a lpha1) Treatment of spatial variation of rho depends on what version of FOAM are you using, but your most important point is to add the non newtonian terms. I'm not an expert in that topic, maybe you can post how the nonnewtonian momentum looks like, so it could be possible to write it in FOAM language. Regards.
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Santiago MÁRQUEZ DAMIÁN, Ph.D. Postdoctoral Fellow Research Center for Computational Mechanics (CIMEC)  CONICET/FICHUNL T.E.: 543424511594 Ext. 1005 Güemes 3450  (3000) Santa Fe Santa Fe  Argentina http://www.cimec.org.ar 

October 10, 2010, 18:36 

#5 
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Eugene de Villiers
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Nonnewtonian viscosity is supported by interFoam just like most of the other incompressible solvers. The constitutive model for fluid viscosity is hiding inside the "twoPaseMixture" model, which is updated inside the turbulence model. At its base, the twoPhaseMixture just combines two runtime selectable viscosity models which could be any of those defined in Foam.


October 10, 2010, 19:06 

#6 
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Santiago Marquez Damian
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Aha, as Eugene said, some lines before there are these ones,
Code:
00001 surfaceScalarField muEff 00002 ( 00003 "muEff", 00004 twoPhaseProperties.muf() 00005 + fvc::interpolate(rho*turbulence>nut()) 00006 ); Best.
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Santiago MÁRQUEZ DAMIÁN, Ph.D. Postdoctoral Fellow Research Center for Computational Mechanics (CIMEC)  CONICET/FICHUNL T.E.: 543424511594 Ext. 1005 Güemes 3450  (3000) Santa Fe Santa Fe  Argentina http://www.cimec.org.ar 

October 11, 2010, 03:03 

#7 
Senior Member

hi buddies
first: as i know the difference between linear or non linear fluid is in the relation between starin and stress so we should consider the non linearity just for viscose term in momentum Equation and it is considered in interFoam , so no more change is needed, am i right? second : where can i find appropriate coefficient for nonNewton fluid, it seems interFoam formula implementation is some how different from typical formulation 

October 11, 2010, 05:54 

#8 
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Eugene de Villiers
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Yes Santiago, you are probably right. In 1.5 there was rasInterFoam and lesInterFoam.
There is already a nearcomplete example of nonNewtonian fluid use in the interFoam tutorials. You just need to change the "transportModel" entry in phase1 or phase2 (or both) to match that you need. Unfortunately, the examples do not detail all the different viscosity models, so you might have to dig into the code to find out which coefficients need to be specified. 

October 11, 2010, 16:03 

#9 
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Santiago Marquez Damian
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Hi, from CrossPowerLaw.C we have:
Code:
00051 Foam::tmp<Foam::volScalarField> 00052 Foam::viscosityModels::CrossPowerLaw::calcNu() const 00053 { 00054 return (nu0_  nuInf_)/(scalar(1) + pow(m_*strainRate(), n_)) + nuInf_; 00055 }
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Santiago MÁRQUEZ DAMIÁN, Ph.D. Postdoctoral Fellow Research Center for Computational Mechanics (CIMEC)  CONICET/FICHUNL T.E.: 543424511594 Ext. 1005 Güemes 3450  (3000) Santa Fe Santa Fe  Argentina http://www.cimec.org.ar 

October 18, 2010, 05:04 
Hi

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Hi guys,
how one can use two differnet viscosityModels in the same solver, and how to call the two viscosities from their models, lets say: transportModel1 PowerLaw, tranportModel2 Crosspowerlaw How is that can be done? i don't need to use turbulence, i need something direct like icoFoam, but i'll define my transportModels in the dictionary. Help please? 

October 18, 2010, 05:22 
hi

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October 18, 2010, 05:46 
HI

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Hi
here are the definitions in constant/transportProperties directory transportModel CrossPowerLaw CrossPowerLawCoeffs { nu0 nu0 [0 2 1 0 0 0 0] 1e06; nuInf nuInf [0 2 1 0 0 0 0] 1e06; m m [0 0 1 0 0 0 0] 1; n n [0 0 0 0 0 0 0] 1; } 

October 18, 2010, 07:54 
HI

#16  
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Quote:
Questions about CrossArrhenius and CrossWLF viscosity model 

Tags 
cross law, interfoam, non newtonian 
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