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June 26, 2013, 05:46 
What is the "dpdt" term?chtMultiRegionFoam

#1 
New Member
Qing, Cao
Join Date: Nov 2012
Posts: 6
Rep Power: 5 
Hi Foamers!
in the energy equation of the solver chtMultiRegionFoam, there is some code like following: fvScalarMatrix hEqn ( fvm::ddt(rho, h) + fvm::div(phi, h)  fvm::laplacian(turb.alphaEff(), h) == dpdt  (fvc::ddt(rho, K) + fvc::div(phi, K)) + rad.Sh(thermo) ); my questions are: 1, what does that "dpdt" means? 2, what does that "rad.Sh(thermo)" means? thank you guys, i am a really newbie in OpenFOAM.. Regards, Qing 

June 26, 2013, 09:21 

#2 
Senior Member
Fumiya Nozaki
Join Date: Jun 2010
Location: Yokohama, Japan
Posts: 193
Rep Power: 9 
Hi,
1. You might want to look at the bottom of this page: http://www.openfoam.org/version2.2.0/thermophysical.php 2. This is the source term from the radiation. Hope that helps, Fumiya 

June 26, 2013, 09:38 

#3  
New Member
Qing, Cao
Join Date: Nov 2012
Posts: 6
Rep Power: 5 
Quote:
for point 1, i read that part but i still dont unterstand the mathematical formula of the dpdt.. Is dpdt the "pressurework term" and what it looks like? Or the dpdt is just a selector? for point 2, what is the mathematical formula of that source term? Does the "Sh" mean Sherwood number? So anyway, if someone can show me the complett mathematical equation of that energy equation code, that will be very nice.. Best regards, Qing 

June 26, 2013, 10:39 

#4 
Senior Member
Fumiya Nozaki
Join Date: Jun 2010
Location: Yokohama, Japan
Posts: 193
Rep Power: 9 
Hi,
1. In the pEqn.H(https://github.com/OpenFOAM/OpenFOAM...m/fluid/pEqn.H) Code:
// Update pressure time derivative if needed if (thermo.dpdt()) { dpdt = fvc::ddt(p); } Code:
Foam::tmp<Foam::fvScalarMatrix> Foam::radiation::radiationModel::Sh ( fluidThermo& thermo ) const { volScalarField& he = thermo.he(); const volScalarField Cpv(thermo.Cpv()); const volScalarField T3(pow3(T_)); return ( Ru()  fvm::Sp(4.0*Rp()*T3/Cpv, he)  Rp()*T3*(T_  4.0*he/Cpv) ); } Hope that helps, Fumiya 

June 26, 2013, 11:08 

#5  
New Member
Qing, Cao
Join Date: Nov 2012
Posts: 6
Rep Power: 5 
Quote:
that s a wonderful answer, have a nice day! Regards, Qing 

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