Statistical analysis on wall shear stress of turbulent boundary layer in achannel flow using micro-shear stress imager

Measurements of wall shear stress of turbulent boundary layers in the chann el flow were carried out using a micro-electromechanical-system (MEMS)-base d micro-shear stress imaging chip. The study was carried out in a turbulent channel Row facility. One array of 25 micro-shear stress sensors in the ch ip that covers a length of 7.5 mm is used to measure the instantaneous span -wise distribution of the surface shear stress. The characteristics of high shear stress area (streaks) were described with statistics. Based on the m easurement, the physical quantities associated with the high shear stress s treaks, such as their length, width with the high shear stress level, were obtained. To further explore the relationship between the shear stress slop e and the peak shear stress, the probability density function (PDF) of the ratio of peak shear stress to shear stress slope at different Reynolds numb er Re is examined. As for the distribution of PDF, it was found that the di stribution concentrated towards a certain value in each RP. This result is extremely important because it points to the possibility of predicting the peak shear stress level based on the shear stress distribution at the leadi ng edge of the streaks. (C) 2000 Begell House Inc. Published by Elsevier Sc ience Inc. All rights reserved.