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

Automatic wall function parameters

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

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   April 6, 2016, 09:55
Default Automatic wall function parameters
  #1
New Member
 
Moritz
Join Date: Apr 2016
Posts: 2
Rep Power: 0
MoritzP is on a distinguished road
Hi,
i've got a question concerning the parameters used in the automatic wall function treatment when using the SST model. I am simulating the case of a temperatur dependent viscosity oil in a 2D-channel with wall heating. As shown in some papers with DNS in this topic, the elevation of the log-layer in the velocity distribution ist highly influenced by the viscosity ratio near the wall due to the heating.
I have already simulated my case with a fine mesh and got the same result for the velocity distribution and the wall shear. Now the aim of that study is to get an acceptable result for a coarse mesh by implementing a model change. Therefore I want to modify the parameter C in the log law used for u_{\tau}: u_{\tau}=\frac{u}{\frac{1}{\kappa}ln(y^{*})+C}
I could not find anything on this case in the manual or other forum threads until now. Thanks for your help in advance
MoritzP is offline   Reply With Quote

Old   April 6, 2016, 20:14
Default
  #2
Super Moderator
 
Glenn Horrocks
Join Date: Mar 2009
Location: Sydney, Australia
Posts: 17,847
Rep Power: 144
ghorrocks is just really niceghorrocks is just really niceghorrocks is just really niceghorrocks is just really nice
Quoting Opaque:

Quote:
After selecting the RNG model, open the Advanced Controls for the turbulence model setup, and overwrite the Eddy Viscosity value by your own CEL expression.
This is in reference to the RNG model but the same thing applies to all eddy viscosity models.

From this thread: http://www.cfd-online.com/Forums/cfx...nce-model.html
ghorrocks is offline   Reply With Quote

Old   April 7, 2016, 11:39
Default
  #3
New Member
 
Moritz
Join Date: Apr 2016
Posts: 2
Rep Power: 0
MoritzP is on a distinguished road
Thanks for your reply Glenn
I wasn't referring to the eddy viscosity but to the wall friction velocity.
Anyway I found a way to modify the wall function for the momentum by activating beta features for physics and implementing a user defined wall function coefficient.
MoritzP is offline   Reply With Quote

Old   April 7, 2016, 19:15
Default
  #4
Super Moderator
 
Glenn Horrocks
Join Date: Mar 2009
Location: Sydney, Australia
Posts: 17,847
Rep Power: 144
ghorrocks is just really niceghorrocks is just really niceghorrocks is just really niceghorrocks is just really nice
Oops, sorry - looks like I did not read your post close enough. Good to hear you found a way anyway.

By the way, you could probably also do this by defining your wall with a specified wall shear stress.
ghorrocks is offline   Reply With Quote

Reply

Tags
automatic wall function, log law, sst

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
decomposePar problem: Cell 0contains face labels out of range vaina74 OpenFOAM Pre-Processing 37 July 20, 2020 06:38
[blockMesh] non-orthogonal faces and incorrect orientation? nennbs OpenFOAM Meshing & Mesh Conversion 7 April 17, 2013 06:42
is internalField(U) equivalent to zeroGradient? immortality OpenFOAM Running, Solving & CFD 7 March 29, 2013 02:27
BSL Automatic Wall Function - Shifted koordinates Sali CFX 0 April 26, 2007 06:04
SST model Autometic wall function parameters? David CFX 0 November 24, 2005 05:47


All times are GMT -4. The time now is 13:05.