SPECIES CONCENTRATION DECAY IN A TURBULENT BOUNDARY LAYER.

Abstract : The streamwise decay of the flux of a chemical species in a turbulent boundary layer with a catalytic wall and zero concentration in the free stream is considered; as occurs, for example, in the boundary layer of a slender blunted cone where the chemical species are created at the nose and swallowed by the boundary layer downstream. First, to compare with previous work on related problems for incompressible flows, a simple power law for the velocity profile was used. For a shear stress normal profile assumed constant an analytical solution is obtained with a flux decay exponent of -0.1. However, that assumption leads to a concentration profile about twice as thick as the boundary layer thickness. The use of a shear stress profile which decreases in the normal direction leads to an exponent of -0.2. The extensions to more complex velocity profile expressions and compressible flow are given. (Author)