CFD Online Discussion Forums

CFD Online Discussion Forums (http://www.cfd-online.com/Forums/)
-   OpenFOAM Running, Solving & CFD (http://www.cfd-online.com/Forums/openfoam-solving/)
-   -   Problem with IcoFoam in parallel (http://www.cfd-online.com/Forums/openfoam-solving/58994-problem-icofoam-parallel.html)

skabilan March 18, 2008 03:39

Hi All, I am running an inc
 
Hi All,

I am running an incompressible transient case using icoFoam on 16 processors (Itanium 2, mpirun). The code stalls for a while (roughly 15 -20 mins) when it gets to solving the pressure equations.

GAMG: Solving for p, Initial residual = 0.0754381, Final residual = 0.00116701, No Iterations 2
time step continuity errors : sum local = 8.18748e-17, global = -3.0093e-18, cumulative = -1.55931e-16
GAMG: Solving for p, Initial residual = 0.0136584, Final residual = 0.00132829, No Iterations 1
time step continuity errors : sum local = 9.01088e-17, global = 2.14171e-19, cumulative = -1.55717e-16

Basically it takes less time to solve the same problem on one processor than in parallel.Can anyone help me with this?
Let me know if you need further information regarding the case.

Thanks in advance.

Warm Regards,
Senthil

hjasak March 18, 2008 04:08

Choose other solver on the pre
 
Choose other solver on the pressure equation - this one obviously does not work.

Hrv

skabilan March 20, 2008 14:35

Hi Hrv, I tried all the oth
 
Hi Hrv,

I tried all the other available solvers for the pressure equation but have the same problem. The fastest is with GAMG on four processors.

Any suggestions or thoughts?

Regards,
Senthil

hjasak March 20, 2008 17:55

Even better: a paper with some
 
Even better: a paper with some results:

CG-AMG paper

You can get one of the test cases

Droplet splash test case

and all the solvers are checked into the SVN version. Why don't you try to reporoduce the results from the paper and tell me what you see.

Please let me know,

Hrv

skabilan March 26, 2008 12:43

Hi Hrv, I have emailed you
 
Hi Hrv,

I have emailed you the results of the droplet splash test on our Altix Itanium machine for 1,2 and 4 processors. Sorry, it was an excel sheet and I did not know how to upload the file on to the forum.

Regards,
Senthil

johndeas March 26, 2008 13:09

http://www.cfd-online.com/cgi-
 
http://www.cfd-online.com/cgi-bin/Op...?pg=formatting

look for the attach{} keyword

JD

skabilan March 26, 2008 14:08

Hi Hrv, Here is the attachm
 
Hi Hrv,

Here is the attachment. http://www.cfd-online.com/OpenFOAM_D...s/mime_txt.gif Droplet_splash.txt

Warm Regards,
Senthil

JD: Thanks for the link

kar March 26, 2008 15:22

Hello, I would like to ask
 
Hello,

I would like to ask a question about parallel: when I do mpirun --hostfile <machines> -np <nprocs> .., what is the correspondence of <machines> file entries and processor numbers? Thanks!

K.

johndeas March 27, 2008 05:45

Running the case droppletSpals
 
Running the case droppletSpalsh directly, strictly following README guidance I also get this error:

--> FOAM FATAL IO ERROR : Unknown symmetric matrix solver CG

Valid symmetric matrix solvers are :

4
(
ICCG
smoothSolver
PCG
GAMG
)


file: /home/flurec/commun/vk/08-03/27-dropletSplash/./system/fvSolution::pcorr a
t line 27.

From function lduMatrix::solver::New
in file matrices/lduMatrix/lduMatrix/lduMatrixSolver.C at line 78.

What is going on ?

dmoroian March 27, 2008 05:53

--> FOAM FATAL IO ERROR : Unkn
 
Quote:

--> FOAM FATAL IO ERROR : Unknown symmetric matrix solver CG
Are you using the development version 1.4.1-dev?

Dragos

hjasak March 27, 2008 05:57

Try this: - go to OpenFOAM-
 
Try this:

- go to OpenFOAM-1.4.1-dev/src and tell me if there is a library called lduSolvers. If so, do

wmake libso lduSolvers

and make sure the library is compiled.

- go to OpenFOAM-1.4.1-dev/applications/solvers/multiphase/interFoam and look at the file Make/options. It should contain a line under EXE_LIBS saying -llduSolvers

if so, type wmake and make sure the executable is built.

- if you are not running OpenFOAM-1.4.1-dev, you will fail somewhere along the way. If you want to have a go with the legacy solvers, go to the test case and look for the file dropletSplash/fvSolution.oldSolvers and use that for system/fvSolution

Hope this helps,

Hrv

johndeas March 27, 2008 07:22

I was using the released versi
 
I was using the released version (and currently checking out the svn...). Sorry for the noise, and thanks for your comments.

johndeas April 1, 2008 05:55

Thank you Hrvoje. After my
 
Thank you Hrvoje.

After my dev version of svn worked, I had to add the -lldusolver to a customized solver. I would'nt have find hit quickly without your post.


All times are GMT -4. The time now is 08:48.