Wrong results in OpenFoam parallel runs

visakhmg · November 8, 2013, 08:39

Hello everyone,
I am runing 3D incompressible cases with simpleFoam as well as porousSimpleFoam in OpenFoam 2.1.1. I have noticed that when i start a parallel run from scratch (from time 0), it gives me wrong results and some times the simulation blows off. But when I start the parallel run after a few (say 50) time steps in seriala and switch on to parallel, it gives me reasonable reults. I am using scotch decomposition method and the domain is relatively bulky. Does the error increase with number of processors I am using? I heard there is some problem with parallelization in OpenFoam 2.1.1. Is it true? And finally, what is the diference between scotch and metis decomposition methods?

wyldckat · November 9, 2013, 14:13

Greetings Visakh,

It doesn't matter as much the version of OpenFOAM you are using, because any version can lead to a crash, if certain details are not taken into account when running in parallel, as listed here: http://www.cfd-online.com/Forums/ope...tml#post324934 - post #28 provides a list of known reasons why a run might not go well in parallel.

Best regards,
Bruno

November 8, 2013, 08:39	Wrong results in OpenFoam parallel runs	#1
visakhmg New Member Visakh Join Date: Dec 2010 Location: Bangalore, India Posts: 7 Rep Power: 15	Hello everyone, I am runing 3D incompressible cases with simpleFoam as well as porousSimpleFoam in OpenFoam 2.1.1. I have noticed that when i start a parallel run from scratch (from time 0), it gives me wrong results and some times the simulation blows off. But when I start the parallel run after a few (say 50) time steps in seriala and switch on to parallel, it gives me reasonable reults. I am using scotch decomposition method and the domain is relatively bulky. Does the error increase with number of processors I am using? I heard there is some problem with parallelization in OpenFoam 2.1.1. Is it true? And finally, what is the diference between scotch and metis decomposition methods?

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November 9, 2013, 14:13		#2
wyldckat Retired Super Moderator Bruno Santos Join Date: Mar 2009 Location: Lisbon, Portugal Posts: 10,982 Blog Entries: 45 Rep Power: 128	Greetings Visakh, It doesn't matter as much the version of OpenFOAM you are using, because any version can lead to a crash, if certain details are not taken into account when running in parallel, as listed here: http://www.cfd-online.com/Forums/ope...tml#post324934 - post #28 provides a list of known reasons why a run might not go well in parallel. Best regards, Bruno visakhmg likes this. __________________ OpenFOAM: FAQ \| Getting started Forum: How to get help, to post code/output and forum guide Read this before sending me PM