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

Does standard k-epsilon predicts poor turbulent shear stress?

Register Blogs Community New Posts Updated Threads Search

Like Tree2Likes
  • 2 Post By sbaffini

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   February 1, 2021, 22:40
Default Does standard k-epsilon predicts poor turbulent shear stress?
  #1
Member
 
Join Date: Feb 2019
Posts: 65
Rep Power: 7
cfdnewb123 is on a distinguished road
I am testing standard k-epsilon model for a 3D test case but its turbulent shear stress is e.g. -uv*1000=~600 while experimental data shows -uv*1000=~3. This applies to uu and vv too. Is this normal for standard k-epsilon model?

Standard k-epsilon model is however able to provide more accurate prediction of turbulent shear stress for 2D case
cfdnewb123 is offline   Reply With Quote

Old   February 2, 2021, 03:23
Default
  #2
Senior Member
 
sbaffini's Avatar
 
Paolo Lampitella
Join Date: Mar 2009
Location: Italy
Posts: 2,151
Blog Entries: 29
Rep Power: 39
sbaffini will become famous soon enoughsbaffini will become famous soon enough
Send a message via Skype™ to sbaffini
The standard k-epsilon model has several flaws, but not all of them are corrected by the other variants.

I don't have a lot of experience in using it (so I can't say if this is your case) but, one of them is indeed the so called "round-jet/plane-jet anomaly", in which turbulent 2d planar jets are, mostly, well predicted but not the 3d round ones. The realizable version, among others, corrects this.

Also, without proper corrections, most k-something models tend, in some circumstances, to overproduce k that, in turn, will give larger eddy viscosities.
cfdnewb123 and aero_head like this.
sbaffini is offline   Reply With Quote

Reply

Tags
rans modelling, shear stress, standard k epsilon


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
Shear Stress Calculation in the flow. auburnuser FLOW-3D 11 May 12, 2018 13:49
Cannot achieve negative wall shear stress values in CFD Post (ANSYS) SAtkins CFX 3 August 3, 2016 14:27
Plotting Shear Stress michael.collins STAR-CCM+ 1 January 21, 2016 11:39
Wall shear stress in channel flow sreeyuth OpenFOAM Running, Solving & CFD 2 September 5, 2014 10:02
Drift-flux model and wall shear stress laoji FLUENT 0 July 8, 2014 22:42


All times are GMT -4. The time now is 17:53.