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-   -   fast way to probe many points? (https://www.cfd-online.com/Forums/openfoam-post-processing/135699-fast-way-probe-many-points.html)

Eloise May 16, 2014 11:02
fast way to probe many points?
 
Hello,
I need to probe many points (order of 10 000) at the end of my simulation. I am currently using the function "probe" in my controlDict, with outputTime at the end of the simulation. It works fine, but it introduce a delay of several hours before the solver actually starts (~10 million cells mesh, running on 64 cores). Therefore, I'm looking for a faster way to probe all those points. Does someone have experience with that?
Thanks for your help!
Eloïse

wyldckat May 17, 2014 13:55
Hi Eloïse,

I assume you're using something similar to the example at "src/sampling/probes/probesDict" and also available at "applications/utilities/postProcessing/sampling/probeLocations/probesDict"?

Have you tried the "cloud" set type for the sampling mechanism, instead of the probes? A full example is given at "applications/utilities/postProcessing/sampling/sample/sampleDict". You need to be more careful with this one, since it has interpolation options; because I'm not sure if the probe function object has interpolation options.

The other possibility is to simply use the utility probeLocations in parallel, after the solver as finished.

Best regards,
Bruno

Eloise May 19, 2014 05:32
Hello Bruno,

Thanks for your answer! I was actually using this code in my controlDict:
Code:
functions
{
probes
    {
        type            probes;

        // Where to load it from
        functionObjectLibs ("libsampling.so");

        // Name of the directory for probe data
        name probes;

        // Write at every timestep
        outputControl  outputTime;

        // Fields to be probed
        fields
        (
            UMean
        );

        probeLocations
        (
        (-20.612 -25.399 -87.200)
        );
    }
}
I've now compared probeLocations and sample (with cloud), both in parallel. ProbleLocations seems to take the same time as my initial setup, while cloud sampling is very fast! But indeed, the interpolation scheme must be chosen carefully!

Best regards,
Eloïse


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