esys-escript

Parallel gmsh reader?

Asked by Matt

After finally getting Escript/Finley built with MPI support, I was disappointed to discover that MPI + gmsh functionality is not yet completed. Nothing like reading everything before doing anything...

Anyway, I'm wondering if I may be able to help get this feature working, as I really could use it. Is there some sort of roadmap available I can look at so as to get me pointed in the right direction?

Many thanks in advance!

-Matt

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Lutz Gross (l-gross) said : 		#1

Matt,

This is on our to do list for quite some time now. Most people convert the gmsh file into a finley file on a single
processor using the GmshReader and finley writer - hence the pressure to implement a parallelized gmsh reader in not very high.

The implementation wouldn't be very hard so as the formats are very similar. Not sure if we find the time to work on this right now but I am happy to help of you want to give it a try.

Lutz

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Matt (matt.s) said : 		#2

Hi Lutz,

Hm, that sound's do-able. Where might I find some documentation on this approach? In particular, I need to be able to maintain tagging from gmsh in order to set up my boundary conditions--is this possible with the approach you have alluded to?

Thanks for your time!

-Matt

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Lutz Gross (l-gross) said : 		#3

Matt,

A starting point would be finley/src/Mesh_read.c which is the reader of the finley input file. The reader avoids
to hold the entire mesh on a single processor but read in junks of the file and then sends it off to create a simple
preliminary distribution of the nodes and elements. The final distribution is a actually done by a finley routine which handling the rest. This can pretty much be translated to gmsh (including tags as supported by the finley input file ).
The only problem is that gmsh support different element shapes and so at one point the reader need to work out what to use and this will require some extra communication.

Lutz

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Lutz Gross (l-gross) said : 		#4

the gmsh reader supports now parallel reading in MPI.

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Matt (matt.s) said : 		#5

Hi Lutz,

That's wonderful! Sorry I got nowhere with this myself but my work changed (then ended) shortly after posting the original question and just sort of trailed off. However, I will likely have direct use for this again in a few months :-)