FFT in OpenFOAM

sreehahaha · April 10, 2023, 12:04

Dear Foamers,

Hope your'e having a good time.

I'm using OF9 to simulate my system, which has a 3D cubic geometry with cyclic bc in all directions. I need to evaluate the 3D Fourier Transform of temperature field in my system. I want to evaluate this on-the-fly to avoid writing output to the case directory that would eat up my storage space.

Has anyone had any experience with performing FFT in OF? I don't think the forum contains much helpful discussions. If you have, could you please share the snippet here? It would be very helpful.

For starters, I'm confused about the type of the field T_hat that is the Fourier transform of my T field. I assume this would be complexField. But I get an error when I use this: calculated number of cells is incorrect.

Many thanks,
SP

olesen · April 13, 2023, 17:39

Some code under src/randomProcesses/noise/noiseFFT that might be useful.

dlahaye · April 14, 2023, 06:19

Alternative is to load data in Paraview and do FFT in paraview.

Other alternative is to search this forum. This FFT issue has been discussed here in the past.

April 10, 2023, 12:04	FFT in OpenFOAM	#1
sreehahaha New Member Sreehari Perumanath Join Date: Jun 2022 Posts: 28 Rep Power: 4	Dear Foamers, Hope your'e having a good time. I'm using OF9 to simulate my system, which has a 3D cubic geometry with cyclic bc in all directions. I need to evaluate the 3D Fourier Transform of temperature field in my system. I want to evaluate this on-the-fly to avoid writing output to the case directory that would eat up my storage space. Has anyone had any experience with performing FFT in OF? I don't think the forum contains much helpful discussions. If you have, could you please share the snippet here? It would be very helpful. For starters, I'm confused about the type of the field T_hat that is the Fourier transform of my T field. I assume this would be complexField. But I get an error when I use this: calculated number of cells is incorrect. Many thanks, SP

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April 13, 2023, 17:39		#2
olesen Senior Member Mark Olesen Join Date: Mar 2009 Location: https://olesenm.github.io/ Posts: 1,715 Rep Power: 40	Some code under src/randomProcesses/noise/noiseFFT that might be useful.

April 14, 2023, 06:19		#3
dlahaye Senior Member Domenico Lahaye Join Date: Dec 2013 Posts: 802 Blog Entries: 1 Rep Power: 19	Alternative is to load data in Paraview and do FFT in paraview. Other alternative is to search this forum. This FFT issue has been discussed here in the past.