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How to evaluate Strouhal Number for a adjustable time step? |
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December 12, 2014, 00:10 |
How to evaluate Strouhal Number for a adjustable time step?
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#1 |
New Member
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Hello all,
I'm working in the case of the flow around cylinder subjected to vortex-induced vibration in the transverse direction to the flow (y axis). How can I evaluate the Strouhal number (vortex shedding frequency) using FFT on the lift coefficient time series if the time-step of the simulation is adjustable? Thanks in advance. |
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December 12, 2014, 01:44 |
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#2 |
Senior Member
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Hi,
You can either use interpolation, i.e. take points with variable interval, build interpolation function and then calculate values at constant interval. Then use FFT. Or you can use The Lomb–Scargle periodogram (http://en.wikipedia.org/wiki/Least-s...le_periodogram). In case of FFT you'll get frequency, in case of Lomb-Scargle you'll get 2*pi*frequency. |
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December 14, 2014, 02:01 |
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#3 | |
New Member
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Quote:
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August 24, 2019, 12:30 |
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#4 | |
Senior Member
Ali Shayegh
Join Date: Oct 2015
Posts: 130
Rep Power: 10 |
Quote:
Assuming we build interpolation function and then calculate values at constant interval, then use fft on ,for example, lift coeff in the case of vortex shedding behind a cylinder to obtain fft vector. Now we have to plot fft vector vs frequency vector in order to ,for example, find maximum amplitude. But, what is frequency vector? How to calculate it? |
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Tags |
adjustable time-step, strouhal number, vortex shedding frequency |
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