CFD Online Logo CFD Online URL
Home > Forums > Main CFD Forum


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

LinkBack Thread Tools Display Modes
Old   February 13, 2006, 06:47
Default Preconditioning
Posts: n/a
Dear Friends,

I am working on preconditioning my existing compressible solver so that I can simulate incompressible flows with good accuracy.(Of course in the limit as M->0, not M=0 though). I have made use of primitive variable formulation in my solver based on [p u v T] along with Weiss-Smith preconditioner and one of the variants of the AUSM scheme.

I have some doubts regarding the characteristic BCs when preconditioning is applied. Could someone clarify as to the changed characteristic BCs to be made use of ? I am presently making use of freestream BCs at the farfield. Is this right ? My test problem is flow past a cylinder with the farfield at 25 diameters.

Regards and Thanks in advance,


  Reply With Quote

Old   February 14, 2006, 03:49
Default Re: Preconditioning
Praveen. C
Posts: n/a
Using freestream bc can hamper convergence since there are lot of fast (relative to flow velocity) acoustic waves at low mach number. They will get reflected from the farfield and can slow down convergence. Also lift might be wrong but may not be an issue for the cylinder case. You can take the preconditioned system and linearize it about the freestream and look at the characteristics of this linear system. Then you can devise boundary conditions based on these characteristics.
  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
Roe implement about preconditioning ricklee Main CFD Forum 7 July 7, 2006 06:14
Re: Preconditioning for moving grids ganesh Main CFD Forum 0 April 6, 2006 06:18
Preconditioning in 3D ganesh Main CFD Forum 0 February 28, 2006 07:39
implementing preconditioning clifford bradford Main CFD Forum 0 October 19, 2000 16:03
local preconditioning Manish Jaiman Main CFD Forum 3 May 1, 2000 08:31

All times are GMT -4. The time now is 02:04.