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

Checkboard Instability

Register Blogs Community New Posts Updated Threads Search

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   March 25, 2003, 06:12
Default Checkboard Instability
  #1
P. Birken
Guest
 
Posts: n/a
For incompressible flows, the flow field can exhibit a checkboard patterned instability. Can this happen also for compressible flows? Do you know literature for this?
  Reply With Quote

Old   March 25, 2003, 19:35
Default Re: Checkboard Instability
  #2
Jonas Holdeman
Guest
 
Posts: n/a
I shouldn't think so. Using the FEM, the velocities are usually good in the presence of the "instability" unless you really screw up your code. The checkerboard should not really be a concern. There is a confusion between the function which projects out the non-solenoidal part of the flow (and which must satisfy the LBB condition) and the pressure (which need not satisfy the LBB condition) because they obey similar equations. The projection function is non-physical and if it exhibits checkerboard, so what?, as long as the velocity is OK. Properly computed from the flow field, the pressure will not checkerboard. The checkerboarding in the projection function arises from the fact that on meshes topologically equivalent to a checkerboard, the continuity constraint must be satisfied separately on the red and on the black squares.
  Reply With Quote

Reply


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
On Combustion Instability liqiang Main CFD Forum 1 January 29, 2012 14:50
Numerical Instability PattiMichelle Phoenics 2 December 26, 2005 20:49
Instability at the onset of natural convection Magherbi Main CFD Forum 0 October 23, 2002 10:53
Instability of convection Zeng Main CFD Forum 0 May 26, 2000 06:39
secondary instability?? Anan Main CFD Forum 2 April 6, 2000 10:48


All times are GMT -4. The time now is 03:05.