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-   -   Help on bc on external tab on numeca the value k-epsilon (http://www.cfd-online.com/Forums/numeca/84606-help-bc-external-tab-numeca-value-k-epsilon.html)

Odusseas February 3, 2011 09:53

Help on bc on external tab on numeca the value k-epsilon
 
Hi there

I have a problem on mumeca

i dont know what parameter i have to put on boundaries for the values k and epislon

i use Turbulent Navier-Stokes , Shear Stress Transport (SST) , for an airfoil


on the tab parameters for boundaries i need to put values for k and epsilon (on external tab)

(i have found the values for the other parameters (density,pressure,...))


Any help??

Thank you a lot

Hamidzoka February 8, 2011 07:04

Dear Andereas;
I depends the physics of the flow. usually turbulent kinetic energy (k) is roughly stated as a fraction of mean flow kinetic energy. for example, in case of an axial turbine k will be estimated as 5 to 20% of mean flow kinetic energy. for the case of epsilon one way is to use turbulent length scale. if inlet flow turbulent length scale is known, you can find epsilon from it.
in case there is no data, you should make some try and error.

i would like to know what type of analysis you are going to perfom in Numeca? if you are to perfom a simple aerodynamic simulation, inlet turbulent characteristics perhaps has a few effect on your results. but if are to simulate a heat transfer analysis (or Conjugate Heat Transfer) "k" and "epsilon" should be carefully specified.

regards


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