ISSN:
1089-7666
Source:
AIP Digital Archive
Topics:
Physics
Notes:
The technique of Rao et al. [J. Fluid Mech. 48, 339 (1971)], which consists of identifying pulses or regions of strong activity in a narrow bandpass filtered signal, is reexamined in the context of Sreenivasan's theory [J. Fluid Mech. 151, 81 (1985)], by applying it to white noise and turbulent signals. For white noise, the dependence of pulse characteristics on the threshold and filter center frequency are in close agreement with the theory. There are, however, important differences between white noise and turbulence results, even when the white noise spectrum is shaped to simulate the turbulent spectrum. For the turbulent signal, the theory is valid only for a range of filter parameters for which the departure of the filtered signal from a Gaussian distribution is small. Using wall shear stress and velocity fluctuations in a fully developed turbulent duct flow, the pulse frequency is found to be closely related to the zero-crossing frequency. It is concluded that the pulse frequency, which is proportional to the Kolmogorov frequency, cannot scale on outer variables.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.866734
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