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

transition in SA turbulence model

Register Blogs Community New Posts Updated Threads Search

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   October 6, 2004, 14:06
Default transition in SA turbulence model
  #1
wassim
Guest
 
Posts: n/a
hi, i was wondering if somebody have tried to work on transition from laminar into turbulent for the Spalart-Allmaras model. comparing the equations used in Fluent to the ones given by the original model it seems it is missing the source term related to transition point and i was trying to add that to the model but i'm facing some problems..
  Reply With Quote

Old   October 9, 2004, 07:20
Default missing terms in SAturbulence model
  #2
SAM
Guest
 
Posts: n/a
r u sure
  Reply With Quote

Old   October 12, 2004, 14:51
Default Re: missing terms in SAturbulence model
  #3
wassim
Guest
 
Posts: n/a
yes, if u compare the paper published by S-A and the equations used in Fluent you will see that the terms concerning the Laminar sublayer are ommitted however this might be replaced by Fluent with the way they calculate their stress equations at the first cell i'm still checking that however there is the last term concerning the fixed transition that S-A uses in their model (ft2*deltaU^2) this is replaced in Fluent by a source term that can be added by the user through a UDF.
  Reply With Quote

Old   October 13, 2004, 01:05
Default Re: missing terms in SAturbulence model
  #4
SAM
Guest
 
Posts: n/a
fluent has already mentionaed that it is low reynolds number model but they aslo said in next paragraph that this can be applied to fully turbulent flow like k-epsilon model

see fluent users guide turbulence modeling
  Reply With Quote

Old   October 14, 2004, 14:01
Default Re: missing terms in SAturbulence model
  #5
wassim
Guest
 
Posts: n/a
for a fully turbulent case, i have no problem but what about cases where there is transition, i mean S_A in Fluent doesnt predict transition it is a fully turbulent model. i tried to do that by seperating the mesh into laminar and turbulent region and this was reflected with better results in my CL and CD but this solution is not practical so what i'm trying to do now is to add some adjustment as a UDF in order to model transition and thus improve my calcualtions.. i really approciate your comments on the subject, thanks
  Reply With Quote

Reply


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
Turbulence postprocessing Mohsin FLUENT 2 October 3, 2016 15:18
build your own turbulence model with buoyancy Thomas Baumann OpenFOAM 11 November 23, 2009 09:53
modelling transition with v2f turbulence model pablo FLUENT 0 August 7, 2006 16:44
Sinclair Model + secondary turbulence Yi FLUENT 0 October 26, 2001 14:37


All times are GMT -4. The time now is 22:52.