CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > Software User Forums > Siemens > STAR-CCM+

Karman Vortex street

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

Like Tree2Likes
  • 1 Post By lava12005
  • 1 Post By anunu

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   December 8, 2011, 11:18
Exclamation Karman Vortex street
  #1
New Member
 
Join Date: Dec 2011
Posts: 13
Rep Power: 14
Apocolapse is on a distinguished road
Hi all,

I am having difficulty producing a karman vortex in Star CCM. I am a new user to the program, so the problem could be any number of things!

I am using a cylinder with a diameter of 0.016m and velocity of 0.0075m/s with water as my fluid.
So, according to the formula here (http://en.wikipedia.org/wiki/K%C3%A1..._vortex_street) I have a reynolds number of ~135. This should be enough to create the karman vortex effect, but my result vortex is different.

Attatched is a screenshot

The physics conditions are:
  • laminar
  • implicit unsteady
  • liquid
  • constant density
  • segregated flow
  • three dimensional

And my mesh uses:
Prism Layer mesher
Trimmer
Surface Remesher

base size = 0.016m
minimum = 25%
Then I created a box in which to make the mesh finer, which can be seen in the image, here the mimimum size is 10%.

I cannot recall my simulation step time, but the image above was obtained after a VERY lengthy run, so there was not going to be much more change.

Could someone please point out where I have gone wrong?

Or, even better, could someone send me a .sim file with the vortex running correctly so I can reverse engineer the problem?

Big thanks to you all
Apocolapse is offline   Reply With Quote

Old   December 8, 2011, 21:00
Default
  #2
Senior Member
 
KHB
Join Date: Aug 2010
Location: Singapore
Posts: 118
Rep Power: 15
lava12005 is on a distinguished road
As far as I know, for low reynolds number it takes quite sometime.
But the wake behind the cylinder has started to oscillate, so what do you mean by the vortex result being different?
Try to calculate the Strouhal number, and compare with the existing data..
Apocolapse likes this.
lava12005 is offline   Reply With Quote

Old   December 12, 2011, 11:53
Default
  #3
New Member
 
Jiashing Liu
Join Date: Mar 2009
Posts: 11
Rep Power: 17
anunu is on a distinguished road
Hi,

Regarding of flow pass through cylinder, you can look for two examples in the user guide. One is in the validation samples, and another is in the aeroacoustic tutorial.


Best Regards,
Apocolapse likes this.
anunu is offline   Reply With Quote

Reply

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
karman vortex street help please SSeth STAR-CCM+ 7 January 10, 2011 12:31
von Karman vortex street. Vortices formation mechanism. mnvl Main CFD Forum 1 February 24, 2010 18:53
Karman vortex street ??? anisa FLUENT 1 May 5, 2005 14:04
Karman vortex street Zhipeng FLUENT 5 June 24, 2002 12:00
Kármán vortex street in cavitating flow behind bodies in the cavitation tunnel L. Könözsy Main CFD Forum 0 April 17, 2000 14:16


All times are GMT -4. The time now is 18:41.