|View Issue Details|
|ID||Project||Category||View Status||Date Submitted||Last Update|
|0002875||OpenFOAM||[All Projects] Bug||public||2018-03-12 13:54||2018-03-12 14:01|
|Priority||normal||Severity||major||Reproducibility||have not tried|
|Status||closed||Resolution||no change required|
|Target Version||Fixed in Version|
|Summary||0002875: Difference parallel and serial running|
|Description||Case description: Air blowing into an open space with only a small wall section. Turbulence model used: RNG kEpsilon|
Problem : When running the exact same case using various methods of decomposition for parallel run on one to 8 processors, the number of iterations before convergence (steady state case) varies greatly (from 245 to 1252), as does one value extracted from each end result (TKE varies from 0.255 to 1.198).
Similar results are obtained for OpenFoam 2.4.
Laminar case was tried for same geometry and initial and boundary conditions with less extreme differences between various decompositions. (though the differences exist)
Issue #0000747 was consulted at https://bugs.openfoam.org/view.php?id=747
describing a similar problem, where it is said to have been resolved, which doesn't seem to be the case?
|Steps To Reproduce||Use uploaded compressed folder containing DecomposePar dictionary for Scotch decomposition into 4 processors. |
mpirun -np 4 simpleFoam -parallel > log &
postProcess -func sampleDict
Look at value k at position (-0.3 6 0) in the last iteration folder in postprocessing folder.
Repeat same actions varying each time the processor decomposition. Results obtained in table below.
|Additional Information||Decompositions tried out Number of iterations before convergence Key value (k at position (-0.3 6 0)|
Simple: 8 (2 2 2) 785 0.711
Scotch: 8 291 0.354
Scotch: 2 375 0.556
Simple: 8 (1 8 1) 348 0.564
Simple: 2 (1 2 1) 513 1.17
Simple:4 (2 1 2) 266 1.15
Scotch: 4 245 0.255
Simple: 8 (4 1 2) 1252 1.198
No Split up (1 processor) 380 0.57
|Tags||No tags attached.|
|We would classify this as user support which would need finance to work on for you.|
|2018-03-12 13:54||Jess||New Issue|
|2018-03-12 13:54||Jess||File Added: simpleductred.zip|
|2018-03-12 14:01||henry||Assigned To||=> henry|
|2018-03-12 14:01||henry||Status||new => closed|
|2018-03-12 14:01||henry||Resolution||open => no change required|
|2018-03-12 14:01||henry||Note Added: 0009414|