Artificial Generation of Thick Turbulent Boundary Layers

Abstract

In order to simulate the turbulent planetary boundary layers accompanied by strong winds, an experimental investigation was performed on two-dimensional thick turbulent boundary layers artificially generated along rough plane surfaces by means of a modified version of turbulence generators originally proposed by Counihan. A circular cylinder whose height was about half that of a turbulence generator was inserted between two consecutive turbulence generators to promote the transverse mixing of flow between them. The experimental results showed that the artificially generated turbulent boundary layers attained an approximate equilibrium state in the region downstream of about 6 times the height of the turbulence generators, where the displacement and momentum thicknesses, shape factor, power-law constant of the mean velocity profile and overall turbulent energy in the boundary layers were almost unchanged in the downstream direction. Thus, the turbulent boundary layers artificially generated in the present experiment could be used to simulate the turbulent planetary boundary layer on the earth.