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

chimera/overset grid questions

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

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   January 3, 2007, 11:13
Default chimera/overset grid questions
  #1
zonexo
Guest
 
Posts: n/a
Hi,

I am now trying to modify my code to enable the use of overset grids. I tried to test my code using a flow past cylinder but there's some unphysical velocity vectors. I wonder what could be the problems...

There's some questions which I would like to ask:

1. I've tried inverse distance and bilinear interpolation. I've read some papers which says least square Taylor series expansion is usually better. Is that so?

2. Is it better for the cylinder grid to be as big as possible, so that the interpolation region is one whereby there's least disturbance?

3. At the location of interpolation, must the cylinder and background grid be of similar size?

Thanks and happy new year!
  Reply With Quote

Old   January 3, 2007, 14:06
Default Re: chimera/overset grid questions
  #2
ag
Guest
 
Posts: n/a
If you are using an unstructured set of grids, then least squares does seem to provide a better interpolation scheme, based on work I have seen. In answer to questions 2 and 3, remember that when you use overset grids you are solving the equations on two different grids - thus you are generating a multiply-defined solution. Therefore interpolation works best in regions of small gradients and between meshes of similar size.
  Reply With Quote

Old   January 3, 2007, 22:59
Default Re: chimera/overset grid questions
  #3
zonexo
Guest
 
Posts: n/a
Thanks ag!

But I'm using structured grid. Is there an interpolation which is more suitable?

Thanks again
  Reply With Quote

Old   January 3, 2007, 23:39
Default Re: chimera/overset grid questions
  #4
Dominic
Guest
 
Posts: n/a
Hi,

Check these out:

A Scheme for Conservative Interpolation on Overlapping Grids, G. Chesshire and W.D. Henshaw, SIAM J. of Scientific Computing, 15, number 4, pp. 819-845 (1994).

Composite Overlapping Meshes for the Solution of Partial Differential Equations, G. Chesshire and W.D. Henshaw, Journal of Computational Physics, 90, number 1, pp. 1-64 (1990)

A Scheme for Conservative Interpolation on Overlapping Grids, G. Chesshire and W.D. Henshaw, SIAM J. of Scientific Computing, 15, number 4, pp. 819-845 (1994).

Regards, Dominic

  Reply With Quote

Old   January 7, 2007, 20:22
Default Re: chimera/overset grid questions
  #5
John Chawner
Guest
 
Posts: n/a
The presentations from the latest Overset Symposium are on-line here: http://www.arl.hpc.mil/events/Overset2006/program.html. Perhaps there's something there that can help.

Also, DiRTlib is a tool that you can use to add overset capability to an existing CFD code. I don't have a URL for it, but you might want to do an internet search.

Hope this helps.
  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
Grid refinement. Sas Main CFD Forum 8 September 2, 2005 09:36
GRID Marc Phoenics 2 August 7, 2002 14:17
Fine grid embedding Philip Peeples Phoenics 1 July 3, 2002 19:32
Combustion Convergence problems Art Stretton Phoenics 5 April 2, 2002 06:59
Numerical methods for discontinuous grid interfaces? Hansong Hang Main CFD Forum 12 September 16, 1998 23:26


All times are GMT -4. The time now is 03:52.