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ISSN Online: 2377-424X

International Heat Transfer Conference 4
August 31 - September 5, 1970, Paris-Versailles, France

THE MECHANISM WHICH CAUSES FREE-STREAM TURBULENCE TO ENHANCE STAGNATION-LINE HEAT AND MASS TRANSFER

Get access (open in a dialog) DOI: 10.1615/IHTC4.1950
pages 1-8

Abstract

The rates of heat and mass transfer across the laminar boundary layer formed in the neighborhood of the forward stagnation line on a two-dimensional blunt body are increased compared with their conventional values (Hiemenz flow) owing to a profound modification of the associated flow field. This modification is produced by an instability which is different from Gortler's and which was first described mathematically by J. Kestin and R. T. Wood. As a result, the flow field acquires a system of evenly distributed, concentrated vortices arrayed in the axial direction and wrapped around the upstream portion of the body; their spacing is inversely proportional to the square root of the Reynolds number. The factor multiplying Re−½ depends on the turbulence intensity, Tu, of the free stream and has a nonvanishing value even for Tu=0, decreasing with an increase in Tu. The local rates of transfer as well as the local shearing stresses at the wall vary in the axial direction and average to values which exceed those calculated for Hiemenz flow.