CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > OpenFOAM Running, Solving & CFD

Bounding problem in running rasinterfoam

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

Reply
 
LinkBack Thread Tools Display Modes
Old   May 1, 2008, 09:31
Default Hello, all, I don't have mu
  #1
Member
 
Quinn Tian
Join Date: Mar 2009
Posts: 62
Rep Power: 8
qtian is on a distinguished road
Hello, all,

I don't have much experience of running the unsteady simulation. I keep getting Bounding warning of k. For the steady case, we can reduce the relaxation factors or change discretization schemes. How about for the unsteady case, if we have similar problem? BTW, checkMesh seems pretty good. Thanks for your help.

Quinn
qtian is offline   Reply With Quote

Old   May 2, 2008, 05:35
Default Hello Quinn, which interpol
  #2
New Member
 
Thomas Ceyrowsky
Join Date: Mar 2009
Location: Germany
Posts: 9
Rep Power: 8
ceyrows is on a distinguished road
Hello Quinn,

which interpolation scheme do you use for the convectice fluxes (the divSchemes entry in the fvSchemes dictionary)?

I think those bounding warnings occur if you get numerical oscillations that depend on the interpolation scheme and mesh resolution. I had the best experiences with "Gauss limitedLinear 1", which behaves relatively stable and gives, in spite of bounding values, relatively good results.

Regards,

Thomas
ceyrows is offline   Reply With Quote

Old   May 2, 2008, 13:31
Default Thomas, I used "Gauss upwin
  #3
Member
 
Quinn Tian
Join Date: Mar 2009
Posts: 62
Rep Power: 8
qtian is on a distinguished road
Thomas,

I used "Gauss upwind" for the convective fluxes. I thought "Gauss upwind" is first order and relatively stable numerically.I will try you suggestion. Have a good weekend.

Qing
qtian is offline   Reply With Quote

Old   May 2, 2008, 14:52
Default Hmmm, this is what I thought,
  #4
New Member
 
Thomas Ceyrowsky
Join Date: Mar 2009
Location: Germany
Posts: 9
Rep Power: 8
ceyrows is on a distinguished road
Hmmm, this is what I thought, too. As far as I know the upwind scheme is bounded by nature and as you say quite stable. But depending on the mesh resolution, it may also introduce a serious error.
So try the limitedLinear scheme anyway. It is also bounded and stable but avoiding numerical diffusion. I also had bounding warnings but the solution did not diverge.

Have a nice weekend too and good luck on monday,

Thomas
ceyrows is offline   Reply With Quote

Old   June 30, 2008, 22:54
Default Hi all, I have got a questi
  #5
New Member
 
Mohd Yousuf
Join Date: Mar 2009
Location: Kharagpur
Posts: 18
Rep Power: 8
yousuf is on a distinguished road
Hi all,
I have got a question, Can we rely on results if "k" and "epsilon" is bounding for few steps??...... (if it is running for 5000 timesteps without any error message)
yousuf 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
SnappyHexMesh plane surface bounding box podallaire OpenFOAM Bugs 22 August 26, 2009 07:34
Bounding epsilon and K with rasInterFoam openfoam_user OpenFOAM Running, Solving & CFD 0 October 23, 2008 08:48
Pressure BCs for rasInterFoam tank fillingdraining problem kwardle OpenFOAM Running, Solving & CFD 8 September 17, 2008 14:37
gridding when bounding surfaces are rough? Herb Schilling Main CFD Forum 1 December 1, 2000 06:58
Bounding frames increments Ricky Wong FLUENT 3 April 6, 2000 08:55


All times are GMT -4. The time now is 18:19.