CFD Online Logo CFD Online URL
Home > Forums > OpenFOAM Running, Solving & CFD


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

LinkBack Thread Tools Display Modes
Old   May 19, 2009, 14:22
Default Relaxation
Senior Member
Antonio Martins
Join Date: Mar 2009
Location: Porto, Porto, Portugal
Posts: 112
Rep Power: 10
titio is on a distinguished road
Send a message via MSN to titio Send a message via Skype™ to titio
Hi all,

I have a small question concerning relaxation. Is there any difference between the two formulations in terms of relative position of relax():

H1: fvVectorMatrix UEqn
+ fvm::div(phi, U)
- fvm::laplacian(, U)

solve(UEqn ==
- fvc::grad(p)

H2: H1: fvVectorMatrix UEqn
+ fvm::div(phi, U)
- fvm::laplacian(, U)

solve(UEqn ==
- fvc::grad(p)

Are H1 and H2 equivalent or different?

António Martins
titio is offline   Reply With Quote

Old   May 20, 2009, 11:11
New Member
Joseph Urich
Join Date: Mar 2009
Location: Pittsburgh, PA
Posts: 16
Rep Power: 10
jurich is on a distinguished road

Your second arrangement will have no effect.

Using relax() with an OpenFoam matrix class enlarges the diagonal terms in the matrix, to increase diagonal dominance. So it must be applied before you call solve().

Once you call solve(), OpenFoam solves the matrix for U, therefore changes to the matrix after that will have no effect on U.

I hope that helps,

Joe Urich
jurich is offline   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
Relaxation and convergence sammi Phoenics 0 March 20, 2008 04:32
Relaxation Factors Tim Phoenics 3 June 30, 2004 02:03
relaxation parameter rvndr Main CFD Forum 0 May 5, 2004 12:34
Question on adjusting relaxation factor CFD Rookie Main CFD Forum 3 January 26, 2004 15:37
Relaxation factor Moon Siemens 1 June 13, 2003 11:13

All times are GMT -4. The time now is 19:49.