CFD Online Logo CFD Online URL
Home > Forums > Software User Forums > ANSYS > FLUENT

Constant value in SA model

Register Blogs Members List Search Today's Posts Mark Forums Read

LinkBack Thread Tools Display Modes
Old   February 20, 2009, 23:29
Default Constant value in SA model
Posts: n/a
How does making ammendment in the constants of the SA model improve my Cd results ??? By decreasing, it take very long to converge yest its not nearer to my experimental results. By increasing the constant, i will get a lot of reversed flow...

Please help!!!!! i really cannot understand....

  Reply With Quote

Old   February 22, 2009, 09:50
Default Re: Constant value in SA model
Posts: n/a

Are you talking about S-A model constants or under relaxation factors. It is not necessary to amend the model constants. For convergence issue decrease the under relaxation factors. What ever the case may be if you are simulating low Re flow then the drag value will be too high. Try to set a small value i.e. 1e-3 or less for turbulent viscosity ratio in the velocity inlet boundary condition. This will solve the reverse flow. Check the previous weeks post, there was some discussions about the Cd.

Cheers, Alagesan.
  Reply With Quote

Old   February 23, 2009, 00:38
Default Re: Constant value in SA model
Posts: n/a
hey thanks a lot.. but i do change my turbulent viscosity in the inlet boundary solution( until to 0.05) but it still varies a lot for the drag value experimental results.

Although i had use High Re no like 2miilion SA model to test for results if it still wont get nearer to experimental drag results Is there any thing goes wrong??? Does refernce values affect the simulation>??

Pls help??
  Reply With Quote


Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

Similar Threads
Thread Thread Starter Forum Replies Last Post
How to keep K constant ??? Ameya Durve FLUENT 3 February 25, 2009 13:00
Roughness Constant Vijay Bhaskar M FLUENT 0 March 11, 2008 10:37
Boussinesq model gives constant density daol FLUENT 2 February 21, 2008 08:51
Questions about model constant of Cmu in Fluent Pingzhi Fang FLUENT 0 January 21, 2008 08:24
K-episilon viscous model----Constant value. Jie FLUENT 3 August 16, 2001 11:55

All times are GMT -4. The time now is 17:17.