School of Engineering, The University of Queensland
Abstract
Reassessment of compiled data reveal that recorded scatter in the hot-wire measured near-wall peak in viscous-scaled streamwise turbulence intensity is due in large part to the simultaneous competing effects of Reynolds number and viscous-scaled wire-length l ( lUt n, where l is the wirelength, Ut is friction velocity and n is kinematic viscosity). These competing factors can explain much of the disparity in existing literature, in particular explaining how previous studies have incorrectly concluded that the inner-scaled near-wall peak is independent of Re. We also investigate the appearance of the, so-called, ‘outerpeak’ in the broadband streamwise intensity, found by some researchers to occur within the log-region of high Reynolds number boundary layers. We show that this ‘outer-peak’ is most likely a symptom of attenuation of small-scales due to large l . Fully mapped energy spectra, obtained with two different l , are presented to demonstrate this phenomena. The spatial attenuation resulting from wires with large l effectively filters small-scale fluctuations from the recorded signal
