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-   -   How define K and epslon for INLET? (http://www.cfd-online.com/Forums/fluent/28418-how-define-k-epslon-inlet.html)

Harry Qiu April 5, 2001 21:32

How define K and epslon for INLET?
 
Dear everyone:

How to define K and epslon for INLET?

thank you

Sincerely, Harry.

manaf hasan April 6, 2001 11:13

Re: How define K and epslon for INLET?
 
why you need to do that? the K & epslon is for the flow inside(interor) onley so you dont have to define K and epslon for the inlet onley .the K & epslon is one kind of modeling the turbelnt flow and should be fixed for all the fluid domain

Chinor April 6, 2001 11:30

Re: How define K and epslon for INLET?
 
You need to specify inlet turbulence quantities. They are an essential part of defining a turbulent flow problem.

k=1.5(U I)^2

U=local velocity magnitude I=turbulence intensity

eps=[(Cmu^.75)*(k^1.5)] / l

Cmu=0.09 (for standard k-eps model) k=turbulent kinetic energy l=turbulent length scale

You can specify other inlet turbulence parameters in Fluent such as turbuelnt intensity & viscosity ratio. You are not limited to specifying k&eps.

Chinor


manaf hasan April 6, 2001 11:36

Re: How define K and epslon for INLET?
 
thank you Chinor for this useful information can you forward to me the refrences that you get your equations from so i can read all the realted articels thanks again

Xiao Hu April 13, 2001 16:16

Re: How define K and epslon for INLET?
 
k and e are rarely used directly. Instead, you have three more choices. If you have an internal flow, turbulence intensity and hydraulic diameter is your best choice. If you are soling an external flow, turbulence intesity and turbulence viscosity ratio is your best choice.



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