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-   -   Version 12 speed compared to 11 (http://www.cfd-online.com/Forums/openfoam-solving/60370-version-12-speed-compared-11-a.html)

maka September 27, 2005 16:19

I ran cavity case 200x200 both
 
I ran cavity case 200x200 both with version 1.1 and 1.2 32 bit,
version 1.2 took 2237 s while,
version 1.1 took 1322 s

version 1.2 was 0.6 times slower than 1.1. I checked the solver output at Time = 0.33, version 1.2 is taking much more iterations to reach the the solution compared to 1.1. I then cheched the case description in both versions, there was one difference in system/fvSolution dictionary:

PISO
{
nCorrectors 2;
nNonOrthogonalCorrectors 0;
pRefCell 0;
pRefValue 0;
}

the last two line in the PISO dictionary has been added in 1.2. I also noticed some small changes that has been done in icoFoam.C solver (is it just a syntax change). Can any body explain what is the reason behind the speed difference. Here is some output. Thanks!

------------------------------------
version 1.2
-------------------------------------
Time = 0.33

Mean and max Courant Numbers = 0.113538 0.985332
ICCG: Solving for p, Initial residual = 1.1225e-06, Final residual = 9.13572e-07, No Iterations 48
time step continuity errors : sum local = 8.49873e-11, global = -9.80646e-20, cumulative = 4.47845e-18
ICCG: Solving for p, Initial residual = 1.74346e-06, Final residual = 9.19236e-07, No Iterations 49
time step continuity errors : sum local = 8.649e-11, global = 2.55935e-20, cumulative = 4.50405e-18
ExecutionTime = 2123.82 s

---------------------------------
version 1.1
---------------------------------
Time = 0.33

Max Courant Number = 0.985328
ICCG: Solving for p, Initial residual = 1.1782e-06, Final residual = 9.46485e-07, No Iterations 1
time step continuity errors : sum local = 8.90883e-11, global = 1.01824e-19, cumulative = -3.82427e-18
ICCG: Solving for p, Initial residual = 1.19506e-06, Final residual = 8.92651e-07, No Iterations 7
time step continuity errors : sum local = 8.43076e-11, global = -1.2003e-19, cumulative = -3.9443e-18
ExecutionTime = 1190.61 s



Regards,
Maka

liugx212 December 14, 2005 20:16

Hi Maka: have you solved yo
 
Hi Maka:

have you solved you problem?
I encounter the same question. Could you please help me?

Thanks a lot.
Guoxiang

maka December 21, 2005 06:42

It seems that there is somethi
 
It seems that there is something that we do not know, that is why no body answered the question. If you managed to know why, I will be grateful if you share the knowledge.

best regards,
Maka


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