CFD Online Discussion Forums

CFD Online Discussion Forums (http://www.cfd-online.com/Forums/)
-   FLUENT (http://www.cfd-online.com/Forums/fluent/)
-   -   size of first cell near wall for k-epselon model (http://www.cfd-online.com/Forums/fluent/33621-size-first-cell-near-wall-k-epselon-model.html)

mukkarum April 30, 2004 02:46

size of first cell near wall for k-epselon model
 
Hi

In a case file when I am using Laminar, solution is going to converge but with turbulent k-epselon standard wall function, solution is not going to converge. For turbulent k-epselon medel we have to have first node within the viscouse sub layer. Anyone may please provide me details of calculating the size of first cell near wall for turbulence model?

Thanks & Regards Mukkarum Hussain


ap April 30, 2004 04:24

Re: size of first cell near wall for k-epselon mod
 
You need to respect the condition:

30 < y+ < 60

You can check the value of y+ in the Adapt-> Y+/Y* panel, which also allows you to adapt the grid in order to respect this condition.

Hi :)

ap

co2 May 8, 2004 21:17

Re: size of first cell near wall for k-epselon mod
 
if i am using k epsilon with std. wall treatment for low reynolds number flow, to maintain y+ between 30 and 60, the grid becomes too coarse. Is it wrong to use k epsilon with std. wall for low Re flow? (In my case low Re flow is buoyancy driven) -- which turb model will be best?

ap May 11, 2004 04:10

Re: size of first cell near wall for k-epselon mod
 
For low Reynolds number you could try the enhanced wall treatment, which requires y+ close to 1.

Hi :)

ap


All times are GMT -4. The time now is 21:06.