CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > Software User Forums > ANSYS > FLUENT

Spalart Allmaras Y-Plus Recommendation

Register Blogs Community New Posts Updated Threads Search

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   June 3, 2017, 21:08
Default Spalart Allmaras Y-Plus Recommendation
  #1
New Member
 
Abhimanyu
Join Date: Jul 2014
Posts: 19
Rep Power: 12
abhi.jam22 is on a distinguished road
Hey guys,

I am performing URANS wing simulations for naca 4415 profile ,Re 3 million, using FLUENT for alpha range from 0 - 90 deg (not dynamic pitching). Now, in order to achieve y-plus 1 and cell aspect ratio of less than 10k for fluent to work properly, the cell count has gone insanely high for a structured grid.

I am trying to make a hybrid mesh with hex cells in a near-field region surrounded by tets outside to reduce the cell count and maintain the aspect ratio in the required range.

Another thing I wanted to explore was increasing the y-plus value to 5 or something beyond 30, say 50, to get rid of the aspect ratio issue, but I wanted to know if that is recommended for SA model. How accurate are the wall functions in FLUENT for SA?

Also, is there an alternative way to approach this problem so that I have a good quality mesh with the required y-plus of 1?

Separation point is an important parameter I am looking at, hence accuracy of model is necessary.

Any guidance is appreciated.

Regards
abhi.jam22 is offline   Reply With Quote

Old   June 5, 2017, 13:41
Default
  #2
New Member
 
Abhimanyu
Join Date: Jul 2014
Posts: 19
Rep Power: 12
abhi.jam22 is on a distinguished road
Bump thread
abhi.jam22 is offline   Reply With Quote

Old   June 6, 2017, 10:42
Default
  #3
Member
 
Quang Le Dang
Join Date: Jun 2012
Posts: 61
Rep Power: 14
SPH_CFD is on a distinguished road
Quote:
Originally Posted by abhi.jam22 View Post
Hey guys,

I am performing URANS wing simulations for naca 4415 profile ,Re 3 million, using FLUENT for alpha range from 0 - 90 deg (not dynamic pitching). Now, in order to achieve y-plus 1 and cell aspect ratio of less than 10k for fluent to work properly, the cell count has gone insanely high for a structured grid.

I am trying to make a hybrid mesh with hex cells in a near-field region surrounded by tets outside to reduce the cell count and maintain the aspect ratio in the required range.

Another thing I wanted to explore was increasing the y-plus value to 5 or something beyond 30, say 50, to get rid of the aspect ratio issue, but I wanted to know if that is recommended for SA model. How accurate are the wall functions in FLUENT for SA?

Also, is there an alternative way to approach this problem so that I have a good quality mesh with the required y-plus of 1?

Separation point is an important parameter I am looking at, hence accuracy of model is necessary.

Any guidance is appreciated.

Regards
First of all, your model is 2D or 3D? And mesh size you have for wallYplus 1?
SPH_CFD is offline   Reply With Quote

Old   June 6, 2017, 11:43
Default
  #4
New Member
 
Abhimanyu
Join Date: Jul 2014
Posts: 19
Rep Power: 12
abhi.jam22 is on a distinguished road
I am performing wing simulations for constant chord (1m) and different aspect ratios of 8,12,16, hence 3D. For y-plus 1, my first cell height is 8.5e-6 m. Total mesh count is around 70 million.
abhi.jam22 is offline   Reply With Quote

Reply

Tags
spalart allmaras, spalart allmaras model, turbulence, unsteady, wing


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 Off
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
A problem about using the Spalart Allmaras model shiningkissss CFX 4 April 23, 2017 23:28
CFX Spalart Allmaras turbulence models aweizazuji CFX 9 September 24, 2013 11:53
Spalart Allmaras Paper Seroga Main CFD Forum 0 April 7, 2008 03:48
spalart allmaras paper hafiz Main CFD Forum 1 April 10, 2007 04:47
extracting K and Epsilon from Spalart Allmaras Sundar Main CFD Forum 4 July 31, 2006 03:02


All times are GMT -4. The time now is 11:39.