CFD Online Discussion Forums

CFD Online Discussion Forums (http://www.cfd-online.com/Forums/)
-   FLUENT (http://www.cfd-online.com/Forums/fluent/)
-   -   Turbulence and Laminar model for empty narrow chan (http://www.cfd-online.com/Forums/fluent/34754-turbulence-laminar-model-empty-narrow-chan.html)

KKLAU October 4, 2004 04:04

Turbulence and Laminar model for empty narrow chan
 
To CFD experts,

i am simulating the flow of a fluid in a narrow channel. I am sure this narrow channel will generate laminar flow since it is empty and Re < 1000. However, when i tried to simulate under laminar /turbulence(k-e) model, it gives different answer in term of velocity distribution for both models. May i know what makes this different ?

Thank you..

From KKLAU

John Luo October 4, 2004 07:49

Re: Turbulence and Laminar model for empty narrow
 
Normal k-e turbulence inherently assumes that the Reynolds number is high and the flow is fully turbulent. That is, it can't simulate either laminar flow or transition. If you switch k-e on numerically, then it will generate turbulent viscosity and thereby additional diffusion, leading to a different solution from laminar one. There are low-reynolds number version of k-e which may performance better.

KKLAU October 4, 2004 22:51

How can i set k-e model for low Re??
 
To fluent experts:

How can i set k-e model for low Reynolds number? Is it same with the k-e RNG model????

From

KKLAU

SAM October 5, 2004 02:35

Re: How can i set k-e model for low Re??
 
USE ENHANCED WALL TREATMENT OPTION

SAM October 5, 2004 04:11

Re: How can i set k-e model for low Re??
 
Enhanced wall treatment use to resolve viscous sub layaer so u have to be care ful for y plus values in ur calculation


SAM October 18, 2004 17:36

Re: How can i set k-e model for low Re??
 
now i have found something new

to use the ke with low Re number use this command

/define/models/viscous/turbulence-expert> low-re-ke Enable the low-Re k-epsilon turbulence model? [no] yes

this will help u i hope

regards



All times are GMT -4. The time now is 07:13.