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

Solving the momentum equation

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

LinkBack Thread Tools Display Modes
Old   January 10, 2008, 11:39
Default Hi all! I have a simple que
Posts: n/a
Hi all!

I have a simple question, which may be a bit dumb but I cannot see immediately the answer. May be a case of "sitting too many hours in front of the PC" syndrom but I try it anyway:

When I look at the output from a transient icoFOAM for example we see that FOAM solves (in 2D say) first the U-momentum equation, then the V-momentum equation and then the respective PISO correctors. Correct so far? Or am I missled by the output on the screen?

I further assume that the scheme is implicit.

If the above is correct then you have to iterate over the U-V momentum equations using ADI for example, in order to get the change of V into U and vice versa, or? Or solve a coupled system of the moemtum equations. Otherwise it would not be explicit anymore and possibly not correct at all.

Am I missing something? Guess I am. Looking forward to the discussion!

Kind regards,


PS: Would it be possible to get FOAM 1.5 into the svn? Maybe on a "here it is but do not dare to email if something does not work yet" basis? That would be really great! Keep up the good work!
  Reply With Quote

Old   January 10, 2008, 17:54
Default I meant to write "Otherwise it
Posts: n/a
I meant to write "Otherwise it would not be implicit anymore and possibly not correct at all." of course ...


  Reply With Quote

Old   January 11, 2008, 08:24
Default Dear Markus, Having a look
Patricio Bohorquez
Join Date: Mar 2009
Location: Jaén, Spain
Posts: 95
Rep Power: 10
pbohorquez is on a distinguished road
Dear Markus,

Having a look at icoFoam solver:

you will realize that UEqn is constructed using a complete implicit method (fvm:: is employed to discretize all the differential operators).

These momentum equations are solved together with the continuity equation using a PISO loop (see, for instance, the comment by Hrv that follows

or references in the Wiki cited above). Therefore, the Implicitly Discretized Fluid Flow Equations are not solved with a block-coupled approach, but this does not mean that icoFoam is not implicit anymore.

Does that make sense?

Best wishes,
pbohorquez 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
Momentum Equation Munir Ahmed Khan FLUENT 0 August 27, 2008 07:57
Solving the turbulence equation summer FLUENT 4 July 13, 2007 09:57
Pressure BC by solving momentum eq sshyu OpenFOAM Running, Solving & CFD 3 January 23, 2006 11:23
Momentum Equation Andrew CFX 1 July 25, 2003 15:38
momentum equation cfp CFX 0 July 8, 2002 04:48

All times are GMT -4. The time now is 20:55.