FREQUENCY DISTRIBUTIONS OF VELOCITIES IN TURBULENT FLOW

Abstract

A conventional anemometer used in the atmosphere or in a wind tunnel measures velocities projected on a plane independently of their directions in the plane. The relation between the frequency distribution of those velocities and the frequency distribution of the turbulent components parallel to the direction of the mean velocity is discussed. At small intensities of the longitudinal turbulence the two distributions are approximately the same. However, at intensities of turbulence of the order of those measured in the atmosphere, the difference between the two frequency distributions becomes appreciable. Some experimental frequency distributions of wind velocities are presented, and the intensities of atmospheric turbulence are determined from the experiments.