CFD Online Discussion Forums

CFD Online Discussion Forums (http://www.cfd-online.com/Forums/)
-   FLUENT (http://www.cfd-online.com/Forums/fluent/)
-   -   a problem (http://www.cfd-online.com/Forums/fluent/31010-problem.html)

liu March 2, 2003 08:40

a problem
 
When I use Fluent to compute 3D flow field, the following information appears: ˇ°Turbulent viscosity limited to viscosity ratio of 1.000000+05 in 18 cells.ˇ± What does it mean? Do I need to reset any parameters? Do it affect computation results? Thank you!

zhhuang March 3, 2003 01:14

Re: a problem
 
1/check your model, shape and size,Maybe the size 2/check your fluid,the default is air,maybe your fuild is water or others

Raintung March 3, 2003 03:08

Re: a problem
 
I met with the same phenomenon. Can you explain in detail, please? What does the ˇ°sizeˇ± mean? The solver used is coupled and explicit. Thank you very much!

ff March 3, 2003 05:24

Re: a problem
 
Read in fluent user guide chepters about turbulence modeling and/or some books about turbulent modeling.

Regards, ff

zhhuang March 3, 2003 08:15

Re: a problem
 
Raintung,I mean maybe you create your model in Gambit,and the default length unit in Gambit is meter.while the real unit maybe is mm.But you forgot to scale the unit in Fluent,and the inlet mass is constant,the velocity will be dimiss.I hope I didn't confuse you! regards zhhuang

Raintung March 3, 2003 09:51

Re: a problem
 
Thank you! But,are there any other reasons? I don't know what should I do.

Marc Gugau March 5, 2003 05:03

Re: a problem
 
It means your turbulence model (I guess Standard k-e !?) calculates a turbulent viscosity that is higher than the maximum allowed value (solve/controls/limits). This often happens in stagnation points. You can check out the 18 cells by displaying 3d-contours of the interior-zone with a lower limit of 1e5. Furthermore you can avoid all this by choosing a more sophisticated turbulence model. Neverthless your computational result should only neglectably be affected.


All times are GMT -4. The time now is 06:41.