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-   -   Slow interFoam compared with other CFD tools? (http://www.cfd-online.com/Forums/openfoam-programming-development/82108-slow-interfoam-compared-other-cfd-tools.html)

Ralph M November 17, 2010 06:20

Slow interFoam compared with other CFD tools?
 
Good morning OF users,

My background is naval architect and thus i like working with ships and yachts. I'm making use of shipFoam, a modified version of interfoam to incoorporate a 6DoF motion of a ship in a multiphase flow.

With recent discussions I discovered that the interFoam solver is significant slower than other VOF methods for free surface flows from other (commercial) software. I heard that the main problem was the control of the Courant number which is the limiting factor for a stable calculation in interFoam.

I took a look in the current solvers (pcorr=PCG with GAMG preconditioner; p_rgh=GAMG; p_rghFinal=PCG with GAMG preconditioner; U=smooth solver; cellMotionU=PCG) and compared them with earlier data and comments from prof Jasak. The solvers seem to be the right one for this specific problem so I wonder if there is something else which can be done to speed up the calculations?

I hope that some of you have some clues how to solve this problem.

Cheers,

Ralph

PS: I started a usergroup for ship hydromechanics (interfoam, interdymfoam, shipfoam, etc). Please join this group if you are interested in working with CFD and ships and also like to share ideas!

Ralph M November 17, 2010 07:46

Hello all,

Some more research learned me that it should be possible to tweak a bit in the /src/cfdTools/incompressible/CourantNo.H file (after making a back-up:D) and link the courant number for example to alpha.

Furthermore the usage of the SIMPLE solver (instead of the PISO) should be possible for steady solutions? This was described for OF1.1 or something; is this still relevant?

Where can I find "compression coefficients" and what is their function?

Above info is mainly found here: http://www.cfd-online.com/Forums/ope...am-solver.html

Ralph


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