CFD Online Discussion Forums

CFD Online Discussion Forums (https://www.cfd-online.com/Forums/)
-   OpenFOAM Programming & Development (https://www.cfd-online.com/Forums/openfoam-programming-development/)
-   -   .boundary() in parallel (https://www.cfd-online.com/Forums/openfoam-programming-development/111479-boundary-parallel.html)

nlinder January 8, 2013 07:50
.boundary() in parallel
 
Hi,

in my solver I have a loop through all my boundaries to extract those of type wall. This is realised by
Code:
forAll (mesh.boundary(), patchI)
{
    if (mesh.boundary()[patchI].type() == "wall")
    {
        wallPatchID = patchI;
       
        Info << "U.boundaryField()[wallPatchID].size(): " << U.boundaryField()[wallPatchID].size() << endl;
...
The output of the Info statement on a single core is correct:
Code:
U.boundaryField()[wallPatchID].size(): 2500
If I run it in parallel with two domains the output is
Code:
U.boundaryField()[wallPatchID].size(): 0
How can I make that work in parallel? What changes when I run this in parallel concerning the numbering of the boundary-patches?

Thanks in advance!
Nicklas

nlinder January 11, 2013 08:18
After playing around with the decomposition methods, I looks as if the code only "runs" on the processor0. Anyone knows what to do?

Thanks

MartinB January 11, 2013 08:26
Hi Nicklas,

use "Pout<< " instead of "Info<< ", then each processor will output its local size.

With "Info<< " only processor0 will print its value, and you must use a gSum command to gather the information from all processors to processor0 first.

Martin

nlinder January 11, 2013 08:33
Hi Martin,

thanks for the hint.. Ok, for the output it is clear. But if i e.g. want to set U as U^2 on a boundary I first have to "gSum" the velocity fields, then square them, and redistribute?

Nicklas

MartinB January 11, 2013 08:36
Since every processor calls the gSum, too, the sum is distributed already, I think. So every processor can calculate the U^2 value and set it locally.
You can check it with the Pout command again.

Martin

nlinder January 11, 2013 08:37
Allright, I'll try that, thanks for your help!

nlinder January 11, 2013 08:59
Sorry to bother again, but...
gSum returns only the sum.. I actually want a vector(or scalar)Field of a patch which is split to several processors. That seems to be sth different?!

Greetings
Nicklas

MartinB January 11, 2013 09:25
May be you can find the answer in this code snippet, where slave processors are sending data to the master processor with Pstream:
http://www.cfd-online.com/Forums/ope...tml#post282446

Martin

nlinder January 11, 2013 10:00
Hi Martin,

I think I now understood what was going wrong. I just added a condition, that the operations on the boundary are only performed, if it's size is greater than 0. No all warnings and Errors disappeared and it seems to work!
Thanks for your help!

Nicklas


All times are GMT -4. The time now is 21:51.