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boundary conditions for K and Epsilon

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Old   January 2, 2001, 09:08
Default boundary conditions for K and Epsilon
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I make modeling of the air flows in the greenhouses with the model K-epsilon and I ask you which values for the boundary conditions I must put in inlet for the turbulent kinetic energie (k) and for the dissipation of this energie (epsilon)?
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Old   January 2, 2001, 11:07
Default Re: boundary conditions for K and Epsilon
Ghanshyam Singh
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What is the Reynolds number in your case? Just to begin with, you can assume turbulent intensity around 5% at the inlet. Calculate K and epsilon based on this and compare the results with the experimental data. You may get reasonable match.

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Old   January 3, 2001, 01:22
Default Re: boundary conditions for K and Epsilon
Abhijit Tilak
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To start with as mentioned by Ghanshyam u need to know typical values of turbulent intensity in flows u are solving. then assume some value of eddy viscosity say Mu_eff=20*Mu_laminar (to be correct molecular viscosity) then calculate k as

k_inlet= (U_in*TU)**2 Tu=turbulent intensity.

U_in=sqrt(u*u+v*v+w*w) e_inlet= (Cmu*rho_inlet*(k_inlet)**2)/Mu_eff

hope this helps

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