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

a problem of valve simulation in openfoam

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

Reply
 
LinkBack Thread Tools Display Modes
Old   January 20, 2011, 08:59
Default a problem of valve simulation in openfoam
  #1
Member
 
chenkai
Join Date: May 2010
Location: munich
Posts: 44
Rep Power: 7
xck1986 is on a distinguished road
Dear FoamUsers,
I am now using the compressible Solver rhoSimpleFoam (steady state case) to simulate a valve.
But I always have the problem of the residuals oszillation, especially for the pressure. see the residual figure in attachment.
I have try to modify the relaxtionfactor for every variable, but it still has oszillation.
Is that possible that the problem was linked to my mesh? Because some boundary elements in my mesh is very small.
The whole case foleder can be found under the fokllowing link:
http://www.youzihui.com/klaus_upload...uestion.tar.gz
Thanks a lot!
Attached Images
File Type: jpg residuals.jpg (57.8 KB, 47 views)
xck1986 is offline   Reply With Quote

Old   January 20, 2011, 15:10
Default
  #2
New Member
 
Bruno F.
Join Date: Feb 2010
Location: Boulder, CO
Posts: 17
Rep Power: 7
fletc900 is on a distinguished road
Hi there. I've had CFD simulations before (not in OF) in which the residuals would oscillate like yours...that doesn't specifically mean that your simulation has not converged. It depends on how OF is calculating the residuals. Are the residual calculations in OF normalized by the average first N iterations? This is something to investigate...

Have you checked other measures for convergence? Such as mass flow rate in - mass flow rate out? Does this value oscillate too?

Cheers
fletc900 is offline   Reply With Quote

Old   January 21, 2011, 21:08
Default
  #3
Senior Member
 
aerothermal's Avatar
 
Guilherme da Silva
Join Date: Aug 2010
Location: Sao Paulo - Brazil
Posts: 105
Rep Power: 6
aerothermal is on a distinguished road
xck1986,

I agree with fletc900.
what are your results for x,y,z forces or moments?
are they converged?

regards,

guilherme
aerothermal 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
Problem with using oscillatingFixedvalue in OpenFoam 1.6 markong OpenFOAM 2 September 16, 2010 06:05
Cross-compiling OpenFOAM 1.7.0 on Linux for Windows 32 and 64bits with Mingw-w64 wyldckat OpenFOAM Announcements from Other Sources 3 September 8, 2010 06:25
How to setup problem in OpenFOAM devesh.baghel OpenFOAM 2 December 11, 2009 02:27
Problem compiling OpenFOAM 1.6.x deji OpenFOAM Installation 1 October 7, 2009 23:00
tracer simulation for transient problem. John CFX 0 August 12, 2005 10:37


All times are GMT -4. The time now is 12:58.