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msg30 January 10, 2008 11:39

Hi all! I have a simple que
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!

msg30 January 10, 2008 17:54

I meant to write "Otherwise it
I meant to write "Otherwise it would not be implicit anymore and possibly not correct at all." of course ...



pbohorquez January 11, 2008 08:24

Dear Markus, Having a look
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,

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