Journal of Fluid Mechanics



The ‘bursting’ phenomenon in a turbulent boundary layer


K. Narahari  Rao a1, R.  Narasimha a1 and M. A. Badri  Narayanan a1
a1 Department of Aeronautical Engineering, Indian Institute of Science, Bangalore 12

Article author query
rao kn   [Google Scholar] 
narasimha r   [Google Scholar] 
narayanan ma   [Google Scholar] 
 

Abstract

Using a hot wire in a turbulent boundary layer in air, an experimental study has been made of the frequent periods of activity (to be called ‘bursts’) noticed in a turbulent signal that has been passed through a narrow band-pass filter. Although definitive identification of bursts presents difficulties, it is found that a reasonable characteristic value for the mean interval between such bursts is consistent, at the same Reynolds number, with the mean burst periods measured by Kline et al. (1967), using hydrogen-bubble techniques in water. However, data over the wider Reynolds number range covered here show that, even in the wall or inner layer, the mean burst period scales with outer rather than inner variables; and that the intervals are distributed according to the log normal law. It is suggested that these ‘bursts’ are to be identified with the ‘spottiness’ of Landau & Kolmogorov, and the high-frequency intermittency observed by Batchelor & Townsend. It is also concluded that the dynamics of the energy balance in a turbulent boundary layer can be understood only on the basis of a coupling between the inner and outer layers.

(Published Online March 29 2006)
(Received September 4 1970)



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