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

General question about SST turbulence model

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

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   December 4, 2015, 14:49
Default General question about SST turbulence model
  #1
New Member
 
Richard Renaud
Join Date: Mar 2015
Posts: 6
Rep Power: 11
Richard Renaud is on a distinguished road
I have a general question about when it is beneficial to use an SST turbulence model.

I've been reading up on turbulence lately. Prior to this recent study, I had a habit of using the SST turbulence model without checking the y-plus of my grid. For example, I used SST when modelling a cylindrical feed well with a tangential inlet pipe that contains baffles. Since there are baffles perpendicular to the flow, separation is likely to occur and I thought that SST would be a good choice to model this. However, I checked my mesh and my y-plus is on the order of 100!

I am wondering, as a general question, does SST offer any advantages over a standard k-ε model when the boundary layer is not well refined. If it is computationally infeasible for me to refine the boundary layer with a y+ of 1, would you recommend that I stick with the SST model anyways? Or does the SST model offer no benefits over a k-ε model when the mesh refinement in the boundary layer is insufficient?

Thanks,
Richard Renaud
Richard Renaud is offline   Reply With Quote

Old   December 19, 2015, 05:13
Default
  #2
New Member
 
Syed Aaquib Hazari
Join Date: Apr 2015
Location: Delft
Posts: 16
Rep Power: 11
hazari.aaquib is on a distinguished road
Dear Richard,

If you're planning to use a grid with a large yplus of the order of 100 I suggest that you should use k-e model.
Only if your yplus is less than 2 (it can extend till 4) you should use the SST or k-w model.

At a wall gradients are steep and basically the SST and k-w model directly solve the equations at the grid cells. While k-e uses wall functions to solve the gradients hence less computationally expensive.

Furthermore, SST is a combination of k-w and k-e.

Good luck!
hazari.aaquib is offline   Reply With Quote

Reply
Thread Tools Search this Thread
Search this Thread:

Advanced Search
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 Off
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Hoz to fix Y+ dependence on inlet Mach number? SST turbulence model LuReym CFX 5 January 20, 2015 17:28
boundary and initial condition for SST k-omga turbulence model mb.pejvak Main CFD Forum 3 May 1, 2012 21:06
General question: turbulence and laminar models fluentmonkey Main CFD Forum 12 March 17, 2011 15:47
Low Reynolds k-epsilon model YJZ ANSYS 1 August 20, 2010 14:57
Advanced Turbulence Modeling in Fluent, Realizable k-epsilon Model Jonas Larsson FLUENT 5 March 13, 2000 04:27


All times are GMT -4. The time now is 15:14.