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January 23, 2011, 09:42 
fvc::ddtPhiCorr(rUA, U, phi)

#1 
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ata kamyabi
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Hi FOAMers
can any one tell me fvc::ddtPhiCorr(rUA, U, phi) in icoFoam code is for what? best regards 

January 24, 2011, 13:05 

#2 
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Santiago Marquez Damian
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January 24, 2011, 23:02 
fvc::ddtPhiCorr(rUA, U, phi)

#3 
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ata kamyabi
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Thank you very much


August 19, 2011, 22:29 
http://www.openfoam.com/mantisbt/print_bug_page.php?bug_id=169

#4 
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M. Timaji
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the term Phi in UEqn and PEqn is not exactly the same:
In the UEqn: corrected flux from the previous iteration or timestep, In the PEqn: mass flux without the pressure contribution. The term ddtPhiCorr checks for the dimensional units of U and phi to decide what operation has to be performed, and if phi is defined in terms of mass, a division of phi by rho is performed. This represents a problem in the case of zero density. Such a case cannot happen in singlephase flows, however it might happen in multiphase flows. For example, let's consider a momentum equation in the form ddt(alpha*rho*U) + div(alpha*rho*U*U) = ... where alpha is the phase fraction. The equation is then represented in the code as fvm::ddt(alphaRho, U) + fvm::div(alphaf*phi, U) == ... being phi = rho_f * (U_f \cdot S). In such a case, if my understanding is correct, one should compute surfaceScalarField phi = fvc::interpolate(rho)*(fvc::interpolate(U) & mesh.Sf()) + fvc::ddtPhiCorr(rUA, rhoAlpha, U, phi) At this point, since alpha can be zero, ddtPhiCorr will cause a division by zero. This does not represent a problem in the incompressible case, since the equation can be divided by rho, which leads phi to be a volumetric flux, and ddtPhiCorr would be ddtPhiCorr(rUA, alpha, U, phi). However, if one wants to deal with the compressible case, keeping equations in conservative form, the problem appears. 

August 21, 2011, 03:54 

#5 
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Alberto Passalacqua
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The problem is known and was reported (I guess you read it since you pasted it :P):
http://www.openfoam.com/mantisbt/view.php?id=169
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Alberto Passalacqua GeekoCFD  A free distribution based on openSUSE 64 bit with CFD tools, including OpenFOAM. Available as in both physical and virtual formats. OpenQBMM  An opensource implementation of quadraturebased moment methods. To obtain more accurate answers, please specify the version of OpenFOAM you are using. 

September 10, 2011, 12:47 

#6  
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M. Timaji
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Quote:
Yes alberto I referenced to the link you've mentiond in the title of my post!!! 

February 7, 2013, 23:10 
Simple

#7 
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,...
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Hi FOAMERS
I have modified SIMPLEFOAM for unsteady flows bu adding ddt(U) to the U matrix. Do I also have to add fvc::ddtPhiCorr in PEqu.H to calculate fluxes? How ignoring this term will affect my results? 

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