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

problem with SST k-omega model

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

Like Tree2Likes
  • 1 Post By avi031
  • 1 Post By swiftaircraft

Reply
 
LinkBack Thread Tools Display Modes
Old   January 25, 2012, 05:10
Default problem with SST k-omega model
  #1
New Member
 
Avinash
Join Date: Jan 2011
Posts: 17
Rep Power: 7
avi031 is on a distinguished road
Hi,
I have used SST k-omega model, Realizable and RNG k-epsilon models for a problem involving heat transfer in a duct (internal flow) with a lot separation, reattachment and re-circulations at near-wall regions. Significant differences in wall temperatures are seen between the turbulence models.
Unfortunately very high wall temperatures are obtained with the usage of SST k-omega model compared to the k-epsilon models, which has resulted in bad-comparison with the literature. This finding is contrary to other numerical simulation papers. The re-circulation size in case of SST k-omega model is also very different from the k-epsilon models.
y+ less than 1 was maintained for all the cases.

The reason for high temperatures with the usage of SST k-omega model evades me. Please let me know of your suggestions, as to what can be wrong.

Regards
Avinash
heidar likes this.
avi031 is offline   Reply With Quote

Old   January 26, 2012, 15:38
Default
  #2
Member
 
David Stanbridge
Join Date: Apr 2010
Location: Norwich, UK
Posts: 58
Rep Power: 8
swiftaircraft is on a distinguished road
What other options within the sst model have you turned on?
swiftaircraft is offline   Reply With Quote

Old   January 27, 2012, 00:43
Default
  #3
New Member
 
Avinash
Join Date: Jan 2011
Posts: 17
Rep Power: 7
avi031 is on a distinguished road
SST model with Low-Re corrections was used for the simulation
avi031 is offline   Reply With Quote

Old   January 27, 2012, 04:48
Default
  #4
Member
 
David Stanbridge
Join Date: Apr 2010
Location: Norwich, UK
Posts: 58
Rep Power: 8
swiftaircraft is on a distinguished road
I would turn off this option as by default the k-omega model can resolve through the boundary layer without any corrections being required. My experience with this option in the past has not been that good.
heidar likes this.
swiftaircraft is offline   Reply With Quote

Old   January 27, 2012, 06:53
Default
  #5
New Member
 
Join Date: Nov 2009
Posts: 13
Rep Power: 8
shaoda169 is on a distinguished road
Quote:
Originally Posted by swiftaircraft View Post
I would turn off this option as by default the k-omega model can resolve through the boundary layer without any corrections being required. My experience with this option in the past has not been that good.
The low-reynolds correction option is borrowed from the original k-w model rather than being in the sst k-w equations. It is said that this option should be used with cautions.
shaoda169 is offline   Reply With Quote

Old   January 29, 2012, 18:24
Thumbs up Very nice
  #6
Member
 
heidar jafarizadeh
Join Date: Mar 2010
Location: Iran- Tehran
Posts: 43
Rep Power: 8
heidar is on a distinguished road
Hello

i Have used the all turbulent model for a ribbed roughened square duct. my reynolds number was from 10000 to 100000 in low reynolds number SST model was very bad and for higher than 25000 RNG, RM, SST, and etc exhebited good results
could you tell me more about your dimensions and reynolds number.
As you know the SST model uses K-w in near the wall and uses K-e in far feild if you give more details we could merge in it

Best Regards
Heidar Jafarizadeh
heidar is offline   Reply With Quote

Reply

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
Use of k-epsilon and k-omega Models Jade M Main CFD Forum 13 June 24, 2016 11:57
Superlinear speedup in OpenFOAM 13 msrinath80 OpenFOAM Running, Solving & CFD 18 March 3, 2015 06:36
convergence problem of the SST and RNG k-e model for mixing tank ziyan7 FLUENT 0 March 8, 2011 07:13
Problem importing watertight model into CFX djk1301 ANSYS 3 February 1, 2011 23:04
expert parameters of SST model? David CFX 1 December 2, 2005 07:36


All times are GMT -4. The time now is 21:06.