Turbulent dispersion in a pipe flow

Abstract

AbstractThe nearly homogeneous, isotropic turbulence field in the core of a fully developed pipe flow was chosen as the medium for turbulent dispersion of a smoke tracer injected from a point on the centerline. By using the optical probe technique the fields of the mean and fluctuating point concentration were mapped at several Reynolds numbers, and spectral analyses made of concentration fluctuations on the plume axis. With the use of sheet illumination, the mean and fluctuating components of the integral material concentration in a plume cross section were measured and the fluctuating component was spectrally analyzed. The maximum Reynolds number was 684,000, the maximum ratio of root‐mean‐square concentration fluctuation to mean concentration exceeded 100% for points and 40% for sheets, and the turbulent Peclet number was found to equal 850. The existence of standard flow conditions was confirmed by measurement of the frictional drag coefficient and the mean concentration field.