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fft in openFOAM

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Old   May 14, 2019, 09:48
Default fft in openFOAM
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Manaf Muhammed
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hi

I want to do a FFT of the spatial data, i.e. FFT for the data extracted over a line, This FFT is then computed for each time step in OpenFOAM. Can anybody help me with the same.

Thanking you
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Old   May 23, 2019, 11:11
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Thomas Sprich
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Hi Manaf,

Does an FFT of spatial data make sense? What frequency would you expect to get? The mesh size? What are you trying to achieve?

I would think that you need to record the data at a point verses time and take an FFT of that.

If you really want to do as you describe, you should be able to create a line source in paraview and export that for all times to a spreadsheet or csv file. You would then need to use python or similar to reconstruct the data into a format that you could take an FFT.

I don't think there a native way to do FFT in Openfoam.

Good luck.
Thomas
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Old   May 24, 2019, 06:11
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Thank you sir
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Old   September 10, 2020, 14:56
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Thomas you are wrong!

there a nice little FFT library in OpenFOAM for cartesian meshes

https://cpp.openfoam.org/dev/dir_afc...e9c4c8c41.html


Quote:
Originally Posted by Swift View Post
Hi Manaf,

Does an FFT of spatial data make sense? What frequency would you expect to get? The mesh size? What are you trying to achieve?

I would think that you need to record the data at a point verses time and take an FFT of that.

If you really want to do as you describe, you should be able to create a line source in paraview and export that for all times to a spreadsheet or csv file. You would then need to use python or similar to reconstruct the data into a format that you could take an FFT.

I don't think there a native way to do FFT in Openfoam.

Good luck.
Thomas
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Old   September 10, 2020, 18:13
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I increase the bid:

FFTW is a part of OpenFOAM. You can use FFTW inside OpenFOAM, therefore.

PS: at least the com version.
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