Calculation of Epsilon in LES model

Yuri Almeida · January 15, 2013, 22:05

Dears,

I'm performing flame simulations using the fireFoam solver. The default set for combustion is the eddy dissipation model, which furnishes the equation below for the source term in the species transport eqn:

wFuelNorm_ = C_*rho_*turbulence_.epsilon()
/max(turbulence_.k(),dimensionedScalar("SMALL",dimV elocity*dimVelocity,SMALL))
*min(YFuel , YO2/s.value());

However, the turbulence model utilized is LES OneEqEddy, which does not directly calculate the epsilon. So, where the epsilon calculation is performed? What expression is used for it?

Thanks in advance,

Yuri

gregor · January 17, 2013, 11:55

Hi Yuri,

the oneEqEddy model is derived from the GenEddyVisc model. In GenEddyVisc.H you find that epsilon is computed as

Code:

 ce_*k()*sqrt(k())/delta();

Yuri Almeida · January 18, 2013, 07:43

Hi Gregor,

Now I got it!

Thank you very much!

January 15, 2013, 22:05	Calculation of Epsilon in LES model	#1
Yuri Almeida New Member Yuri Almeida Join Date: Jan 2012 Location: Rio de Janeiro, Brazil Posts: 21 Rep Power: 14	Dears, I'm performing flame simulations using the fireFoam solver. The default set for combustion is the eddy dissipation model, which furnishes the equation below for the source term in the species transport eqn: wFuelNorm_ = C_rho_turbulence_.epsilon() /max(turbulence_.k(),dimensionedScalar("SMALL",dimV elocitydimVelocity,SMALL)) min(YFuel , YO2/s.value()); However, the turbulence model utilized is LES OneEqEddy, which does not directly calculate the epsilon. So, where the epsilon calculation is performed? What expression is used for it? Thanks in advance, Yuri

January 17, 2013, 11:55		#2
gregor Member Gregor Olenik Join Date: Jun 2009 Location: http://greole.github.io/ Posts: 89 Rep Power: 16	Hi Yuri, the oneEqEddy model is derived from the GenEddyVisc model. In GenEddyVisc.H you find that epsilon is computed as Code: ce_k()sqrt(k())/delta();

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January 18, 2013, 07:43		#3
Yuri Almeida New Member Yuri Almeida Join Date: Jan 2012 Location: Rio de Janeiro, Brazil Posts: 21 Rep Power: 14	Hi Gregor, Now I got it! Thank you very much!