502 短時間フーリエ変換による円柱後流の周波数構造(OS4-1 流体における新技術開発-1)(OS4 流体における新技術開発)

概要

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It is known that short-time Fourier transformation and integral wavelet transformation are useful means of time-frequency analysis. In this experimental research, a new analysis way based on these two transformations was introduced, which is called as short-time Fourier transformation with a adjusted window width, to show the variation of vortex shedding frequency in the turbulent vortex street wake of a circular cylinder. By using this way, the low-frequency modulation in the vortex shedding is shown to exist at a Reynolds number as high as 10,000 and different vortex shedding frequencies were detected in the span wise direction. The nonlinear interaction between these different frequencies is thought as the cause of the long time scale fluctuation.
2001-09-25