How to quickly extract a huge number of field files in parallel

eric-meng · January 25, 2021, 05:54

Hi openfoam experts here,

I recently encountered a weird problem to me, where I found the postprocess utility could not perform consistently when using it to extract data from field files onto a surface.

I want to obtain a time history of enstrophy on a surface in the 3D domain, so I firstly ran simulations in parallel using 200 cores to calculate the enstrophy fields. Those fields were output at every 0.01, so that about 10000 fields were generated. Then I ran postprocess also in parallel to extract the info through the -func surfaces objective. However, the performance for different runnings is pretty diversified. Sometimes it can give out 4000 output per run, but sometimes only just a few hundreds. This is much despairing, because I have a lot of cases to deal with.

I didn't dig too much into this at first and didn't realise as well if there might be a convenient way to extract surfaces info in runtime??

Can anyone give me any idea to save this?

The environment is OpenFOAM+ v1712 and processors stored in collocated filehandler.

geth03 · January 28, 2021, 04:17

if i understand you correctly, you want to output a certain quantity just for a surface at runtime.

you can do that with a little bit of coding. you can write a code within controlDict -> functions that writes out that quantity of interest whenever you want.

https://www.openfoam.com/documentati...hp#x7-390002.2

here is an example.

random_ran · January 29, 2021, 18:01

What postprocess utility do you use to extract Enstrophy?

January 25, 2021, 05:54	How to quickly extract a huge number of field files in parallel	#1
eric-meng New Member Join Date: Apr 2018 Posts: 14 Rep Power: 8	Hi openfoam experts here, I recently encountered a weird problem to me, where I found the postprocess utility could not perform consistently when using it to extract data from field files onto a surface. I want to obtain a time history of enstrophy on a surface in the 3D domain, so I firstly ran simulations in parallel using 200 cores to calculate the enstrophy fields. Those fields were output at every 0.01, so that about 10000 fields were generated. Then I ran postprocess also in parallel to extract the info through the -func surfaces objective. However, the performance for different runnings is pretty diversified. Sometimes it can give out 4000 output per run, but sometimes only just a few hundreds. This is much despairing, because I have a lot of cases to deal with. I didn't dig too much into this at first and didn't realise as well if there might be a convenient way to extract surfaces info in runtime?? Can anyone give me any idea to save this? The environment is OpenFOAM+ v1712 and processors stored in collocated filehandler.

January 29, 2021, 18:01		#3
random_ran Member Ran Join Date: Aug 2016 Posts: 69 Rep Power: 10	What postprocess utility do you use to extract Enstrophy? __________________ Yours in CFD, Ran

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January 28, 2021, 04:17		#2
geth03 Senior Member Join Date: Dec 2019 Location: Cologne, Germany Posts: 369 Rep Power: 8	if i understand you correctly, you want to output a certain quantity just for a surface at runtime. you can do that with a little bit of coding. you can write a code within controlDict -> functions that writes out that quantity of interest whenever you want. https://www.openfoam.com/documentati...hp#x7-390002.2 here is an example.