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February 17, 2014, 14:17 |
Fast Fourier Transform (FFT) in Tecplot 360
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#1 |
New Member
Wojo Woyczynski
Join Date: Jan 2014
Posts: 5
Rep Power: 12 |
Hi All,
I am trying to use Tecplot 360 to get the frequency of my wave. I am using the "Fourier Transform" tool in the "Data" menu. For the plot that gets output, the frequency I am getting looks correct but the amplitude is way higher than the amplitude of my wave. What is problem here? Does anybody know the exact fourier equation that Tecplot 360 uses? Thanks |
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May 11, 2014, 06:41 |
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#2 |
Senior Member
Mohsen KiaMansouri
Join Date: Jan 2010
Location: CFD Lab
Posts: 118
Rep Power: 16 |
Dear Wojo
We have encountered the same problem in Tecplot. The Trend of the output graph and the frequency are very similar to the results obtaind using Excel but the amplitude is very high. If we use different Window function (Rectangular, Triangular, Hann, Hamming) then different amplitudes are obtained but all of them are very High. Have you solved this problem? Thanks in advance
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May 12, 2014, 13:01 |
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#3 |
New Member
Jerimiah
Join Date: May 2014
Location: Bellevue, Washington
Posts: 13
Rep Power: 16 |
Hello,
Tecplot 360 uses FFTW to perform the FFT calculation. As with most DFT's a gain or scaling factor is introduced. We have chosen to leave the calculation as is and let the user decide if they need it scaled down. If you divide the amplitude by your sampling size, you should receive a more reasonable value. You can use the Data > Alter > Specify Equations tool to do this. |
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October 23, 2014, 19:57 |
FFT tutorial link
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#4 |
Senior Member
Scott Rumage
Join Date: May 2009
Location: Seattle, WA
Posts: 152
Rep Power: 17 |
Here is a link to a tutorial on performing FFT in Tecplot 360 EX: https://www.youtube.com/watch?v=hDhhpH0fOMA
Scott |
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September 21, 2016, 09:04 |
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#5 |
New Member
freeday
Join Date: Aug 2010
Location: Indonesia
Posts: 17
Rep Power: 16 |
How much I have to scale down? Is there any information about it? Tb4
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October 26, 2017, 12:09 |
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#6 |
Member
Kuldeep
Join Date: Mar 2016
Posts: 33
Rep Power: 10 |
Generally, You can divide magnitude by number of sample data points to get correct amplitude.
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Tags |
fast fourier transform, fft, fourier, tecplot 360 |
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