Comments

Hi Bruno,

For parallel OpenFoam run with distributed storage, does the roots need to be absolute path?
If the local temporary scratch disk for each node was set to an environmental variables "$TMPDIR" (same name but different location), can it be used in the decomposeParDict as follows,

distributed yes;
roots (
"$TMPDIR"
"$TMPDIR"
"$TMPDIR"
);

I suspect OpenFoam will replace $TMPDIR for each roots with path of the master node only (as the application starts on master node). Is there a way to check if the OpenFoam is using the correct distributed storage?

Dear Bruno,

I do not understand well the procedure to obtain the OpenFOAM documentation. I did the following steps in Ubuntu:

sudo apt-get install doxygen
sudo su -c "$WM_PROJECT_DIR/bin/foamExec ./Allwmake > docmake.log 2>&1"

But I do not see the OpenFOAM documentation? Where is it created?

modestly and sincerely
hope u the best successes

Thanks I hope you success

greetings Bruno

I have O.F. 2.1.x on $HOME directory and I did as exactly as You have specified on installing Doxygen. Everything seems correct . However, after
typing in firefox browser, I got nothing.

Would You PLZ hint me how can I use Doxygen documentation on O.F. 2.1.x?

My ubuntu version is 11.10 and my linux architecture is x86_64.

I downloaded doxygen-1.8.7 according to your link (doxygen-1.8.7.src.tar.gz)

-----------------------------------------------------------------------------------------------------------------

The problem solved. 2 errors that I made:
1- Not putting doxygen in $HOME directory
2-Not using binary distribution for linux x86_64. (doxygen-1.8.7.linux.bin.tar.gz)


Regards
Bobi

Hello,
I have some questions regarding ParaView:

1. How to re_built ParaView 3.12.0?

2. Do we need to install a third-party 2.2.1 with OpenFoam 2.2.1 or ParaFOAM is enough for OpenFOAM 2.2.1 to work properly?

3.When I apply the cavity case in paraView 3.12.0 the Apply icom is not activating, what's the problem?

Help me please to answer these three questions.

Many thanks

How about this old problem ? There are changes?

And how can you guarantee the precision in a new simulation case?

Nice post Wyldckat!

The decomposition in geomDecomp.C looks something like this:
nProcessors_!=n_.x()*n_.y()*n_.z().

So the product cannot exceed the number of cores that you specify. If you are running 2D problems and the mesh is more finer in one direction and coarse in the other direction, then cores in the x direction is 1 and you vary the two others as necessary. In 3d, however, you can utilise the cores in all directions. What I have found useful is to dedicate more cores in the direction where the mesh is fine or varies greatly. Also since the product must equal to or be less than the number of crores available, the user is limited in how they can vary the cores in all directions, since the product of the number or cores in each direction cannot exceed the number of cores available.

IN other words trial and error would be the norm.

Hi Kenna,

10 cores are a lot? Not really or - I think 100 cores are okay

Well I know the fact of splitting the mesh in a optimal way so that not only 2 cores get the whole work.

But I just wanted to know if there are any benchmarks where you can see the effect of a "wrong" splitted mesh.

Maybe in time increase of 10% or sth. like that

You want to use the maximum capacity of your cores (10 are a lot cores ). You need to anticipate where in the mesh the biggest work will appear. Those are mostly the regions with high gradients of pressure, velocity or what ever it calculates(cause of more iterations). For example if you have a straight jet stream going parallel to the x-Axis, you should choose something like this (10 1 1) where the x gets sliced 10 times and every part has a piece of a workload. The program will automatically slice in a manner, that every piece has about the same amount of cells. Consider it when you use refined regions.

Also if you use ubuntu you can use the command 'top´ in a further console to look up the actual use of processor capacity.

Dear Bruno,

do you know any Benchmark of using the x,y,z direction and the Splitting of a geometry into different parts like:

what is faster in a Special case:

a) decompose in (10 1 1)
b) decompose in (1 10 1)
c) decompose in (1 1 10)
d) decompose in (2 5 1)
and so on...

Regards
Tobi

Well, 4*2*2 would make 16 Regions. 6*6*1 separations would be 36.
What would work for 12 domains/processors is (3 2 2).
The Numbers represent the slides through the Mesh parallel to the related coordinate-axe.