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

Domain partitioning

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

Reply
 
LinkBack Thread Tools Display Modes
Old   December 3, 2010, 16:22
Default Domain partitioning
  #1
New Member
 
Andy
Join Date: Dec 2010
Posts: 2
Rep Power: 0
andyman is on a distinguished road
I'm writing a relatively simple implementation of 2-D incompressible Navier-Stokes equations for MATLAB. The flow will be unsteady but laminar throughout.

A big irritation is an irregular domain. It would be very helpful if I could chop it up into a series of three or four rectangular domains. My question is, are there rules of thumb about whether this is acceptable from an accuracy perspective?

What I'd like to do is extrapolate the closest interior points to the boundaries at the "doorway" between successive sub-domains so that the output of one chamber is the input to another. I'm concerned that some sort of upstream effect will ruin my results. Any thoughts? I haven't been able to find any literature.
andyman is offline   Reply With Quote

Old   December 4, 2010, 01:26
Default
  #2
Member
 
ganesh
Join Date: Mar 2009
Posts: 40
Rep Power: 7
ganesh is on a distinguished road
Dear Andy,

I haven't worked with MATLAB for CFD, but as far as extrapolation that you mention is concerned, its effect primarily lies on accuracy. A first order extrapolation (use the value as such) leads to formal first order accuracy, a linear extrapolation would lead to second order accuracy (on uniform grids) or atleast lesser errors on irregular grids. To begin with, for sake of validating your code, you could just start off with a first order extrapolation, as it is easier. There wouldn't be issues of "upstream effect ruining results" as long as you use upwinding, and use the right information. This is essentially what parallel unstructured solvers do; domain partitioning is the starting point when parallelising CFD solvers using MPI.

Hope this helps

Regards,

Ganesh
ganesh is offline   Reply With Quote

Old   December 5, 2010, 11:38
Default
  #3
New Member
 
Andy
Join Date: Dec 2010
Posts: 2
Rep Power: 0
andyman is on a distinguished road
ganesh,

Thanks very much for your reply.

I should have said "downstream effects" as I'm concerned that as the flow moves from left to right, the state of the right-most chamber will affect a middle chamber, etc. But I'm hoping that since a boundary condition on the left-most chamber is "driving" the flow, any downstream effects will be drowned out.

I think your thoughts still hold however. Again, thank you very kindly for your time.
andyman 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
Material identification between a flow domain and a porous domain Ervideiro CFX 1 June 1, 2010 09:50
Domain format problem on airfoil flow simulation andrenonaka CFX 5 May 21, 2010 09:00
air bubble is disappear increasing time using vof xujjun CFX 9 June 9, 2009 07:59
CFX Solver Memory Error mike CFX 1 March 19, 2008 08:22
rotating domain in rotating domain, different axis Robert Stringer CFX 3 December 4, 2006 07:04


All times are GMT -4. The time now is 02:01.