The limiting behaviour of the turbulent transverse velocity component close to a wall

Abstract

Electrochemical techniques are used to measure the circumferential component of the velocity gradient s_z at the wall of a pipe through which a turbulent fluid is flowing. The ratio of the root-mean-squared value of s_z to the time-averaged velocity gradient is found to be 0·09 or 0·1, depending on whether corrections are made for frequency response. The frequency spectrum is similar to that for the component of the wall velocity gradient in the direction of mean flow. The amplitude distribution function for s_z is very roughly approximated by a Gaussian distribution.