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March 24, 2015, 15:21 |
FFT transformation
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#1 |
New Member
Harshal
Join Date: May 2014
Posts: 14
Rep Power: 11 |
Can Anyone tell me the FFT value of the following plot for the first period.
The time step is 0.05. for total 55 sec. I got it around 325 with matlab is it correct? Thanx |
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March 24, 2015, 17:05 |
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#2 |
Senior Member
Matt
Join Date: Aug 2014
Posts: 947
Rep Power: 17 |
It would take rainman (or maybe just Dustin Hoffman) to calculate an FFT in their head from an image. At best you can extract the dominant frequency which (for the first period you show) is around 0.0714 Hz (period of about 14 sec).
Also, 325 what? Hz? When I have used Matlab FFT in the past it converts my signal from time domain to frequency domain. I have never seen it return a single value, although, it has admittedly been a while. Part of the problem might be that you are trying to take the FFT of a single period and it is probably not detecting your main mode and is focusing on the minor modes. Again, it’s been a while since I needed to use FFT so if I am wrong, I apologize. |
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March 25, 2015, 15:57 |
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#3 |
New Member
Tim Meier
Join Date: Mar 2015
Posts: 16
Rep Power: 11 |
It looks like you are using STAR-CCM+.
You can calculate an FFT directly in STAR-CCM+ under Tools -> Data Set Functions |
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