Predictions and measurements of non-axisymmetric turbulent diffusion in an annular channel

Abstract

Measurements have been made of radial and circumferential diffusion of a tracer gas in fully developed flow in an annulus. The Reynolds number used was 1.6 × 10 5 and the working fluid was air ( Sc = 1.0). A prediction method is also described using a flow model based on the van Driest mixing length theory. Using a turbulent Schmidt number of unity, comparisons of the predictions and measurements show best agreement when the ratio of circumferential to radial mass diffusivity is chosen at the constant value of two throughout the flow.