buoyancy corrected turbulence models for thermal plumes

derekm · March 14, 2015, 05:00

What buoyancy corrections are available in openfoam for the RANS turbulence models?
My interest is in thermal plumes inside cavities at rayleigh numbers around 10^9 to 10^10. The standard K-e turbulence model gives poor results compared to experiments.
Looking at the paper by Kumar & Dewan 2013, it looks that there are worthwhile improvements possible. Has anyone implemented these corrections or similar in OpenFoam?

agustinvo · March 15, 2015, 05:16

AFAIK, there are no production terms that take into account the buoyancy effects.

Code:

// Turbulent kinetic energy equation
tmp<fvScalarMatrix> kEqn
(
fvm::ddt(k_)
+ fvm::div(phi_, k_)
- fvm::laplacian(DkEff(), k_)
==
G
- fvm::Sp(epsilon_/k_, k_)
);

Code:

// Dissipation equation
tmp<fvScalarMatrix> epsEqn
(
fvm::ddt(epsilon_)
+ fvm::div(phi_, epsilon_)
- fvm::laplacian(DepsilonEff(), epsilon_)
==
C1_*G*epsilon_/k_
- fvm::Sp(C2_*epsilon_/k_, epsilon_)
);

you should check the term you want to include, copy the model and rename it, and include those terms. Then compile you library by including this new directory.

March 14, 2015, 05:00	buoyancy corrected turbulence models for thermal plumes	#1
derekm Senior Member Derek Mitchell Join Date: Mar 2014 Location: UK, Reading Posts: 172 Rep Power: 13	What buoyancy corrections are available in openfoam for the RANS turbulence models? My interest is in thermal plumes inside cavities at rayleigh numbers around 10^9 to 10^10. The standard K-e turbulence model gives poor results compared to experiments. Looking at the paper by Kumar & Dewan 2013, it looks that there are worthwhile improvements possible. Has anyone implemented these corrections or similar in OpenFoam? __________________ A CHEERING BAND OF FRIENDLY ELVES CARRY THE CONQUERING ADVENTURER OFF INTO THE SUNSET

March 15, 2015, 05:16		#2
agustinvo Senior Member Agustín Villa Join Date: Apr 2013 Location: Alcorcón Posts: 314 Rep Power: 15	AFAIK, there are no production terms that take into account the buoyancy effects. Code: // Turbulent kinetic energy equation tmp<fvScalarMatrix> kEqn ( fvm::ddt(k_) + fvm::div(phi_, k_) - fvm::laplacian(DkEff(), k_) == G - fvm::Sp(epsilon_/k_, k_) ); Code: // Dissipation equation tmp<fvScalarMatrix> epsEqn ( fvm::ddt(epsilon_) + fvm::div(phi_, epsilon_) - fvm::laplacian(DepsilonEff(), epsilon_) == C1_Gepsilon_/k_ - fvm::Sp(C2_*epsilon_/k_, epsilon_) ); you should check the term you want to include, copy the model and rename it, and include those terms. Then compile you library by including this new directory.

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