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#1 |
Senior Member
Farzad Faraji
Join Date: Nov 2019
Posts: 175
Rep Power: 5 ![]() |
Energy Spectrum in Three Dimension?
Dear Friends I want to do 3D spectral analysis for energy. My domain is rectangular and it is (0,0,0)*(0.5, 1.0, 0.1), and it is almost like a jet flow(rectangular bubble flow). Now my question is that for FFT, my nodes needs to be equal(Nx=Ny=Nz) OR mesh size needs to be equal(dx=dy=dz)? Thanks, Farzad |
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#2 | |
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Filippo Maria Denaro
Join Date: Jul 2010
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Quote:
You need one or more directions of periodicity and equal step size along such direction |
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#3 |
Senior Member
Farzad Faraji
Join Date: Nov 2019
Posts: 175
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Dear professor Denaro
Based on what you said for powerspectrum in 3D(rectangular), I need to have dx=dy=dz. But what about Nx(kmax=Nx/2 based on Nyquist theory). Since my Ny is larger than Nx what should I do?(Ny is my streamwise direction). And let ask me a radical question; Can I just transfer rectangle to square and do the powerspectrum inside the square? Thanks, Farzad |
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Tags |
energy spectrum, fft, three dimensional |
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