CFD Online Logo CFD Online URL
Home > Forums > FLUENT

Unusual Asymmetry in results

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

LinkBack Thread Tools Display Modes
Old   January 17, 2013, 12:50
Default Unusual Asymmetry in results
New Member
Join Date: Jan 2013
Posts: 10
Rep Power: 6
OMJT is on a distinguished road
Hi everyone,

I have a slight problem. I am using Fluent14 to attempt to model high Re Cylinder Flow in 2D and see if it gives remotely accurate results. There is however something very odd happening with the Lift Coefficient.

The lift coefficient oscillates as it should do with a reasonable period however it does not oscillate around 0 despite the mesh being symmetrical and the flow in being uniform. The mesh is structured and uses 2 Ogrids around each other to mesh the cylinder itself. Around this is H grid. The Cylinder is relatively very small compared the flow domain so edge conditions should not have any effect on the Lift Coefficient.

Any help with this would be much a appreciated.


OMJT is offline   Reply With Quote

Old   January 17, 2013, 14:03
Senior Member
Join Date: Mar 2011
Location: Germany
Posts: 431
Rep Power: 13
cfd seeker is on a distinguished road
You are performing unstaedy simulation? the amplitude of oscillations is small or large?
cfd seeker is offline   Reply With Quote

Old   January 19, 2013, 20:55
New Member
Join Date: Jan 2013
Posts: 10
Rep Power: 6
OMJT is on a distinguished road
Sorry for the late response. I am not sure what you mean by are the oscillations large or small? Relative to what?

It is flow around a cylinder at Re ~ 10^7. So there should be vortices formed around the same diameter as the cylinder. The vortices produced in the simulation however were smaller and the lift force was of relatively small amplitude. This is a turbulent viscocity limit issue. The real oddity is the non-zero mean of the lift force on the cylinder. Could this be to do with the amplitude of the osciallation?


OMJT is offline   Reply With Quote


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
OpenFOAM - Validation of Results Ahmed OpenFOAM Running, Solving & CFD 9 June 22, 2011 18:59
Error exporting results pawan1989 CFX 5 July 5, 2010 19:03
wind tunnel results vs fluent pixie Main CFD Forum 1 August 20, 2009 08:02
Velocity spots in openFoam results Valle OpenFOAM Running, Solving & CFD 4 August 19, 2009 05:53
How to plot a function over a time period? Cirion0000 CFX 4 July 18, 2009 12:48

All times are GMT -4. The time now is 17:19.