Wind and turbulence profiles in a simulated wind tunnel boundary layer

Abstract

A system of Honeycomb Flat Plate (HFP) grid and cylindrical rods has been developed to accelerate the growth of a thick (32 cm) turbulent boundary layer, artificially, over rough floor of a low speed short test-section (0.61 m x 0.61 m) wind tunnel. Simulated profiles of wind velocity, longitudinal turbulence intensity and Reynolds stress are shown to have similarity to those of a neutral atmospheric boundary layer over a typical rural terrain. Longitudinal spectrum of turbulence measured at 10,30 and 100 mm above tunnel floor is shown to compare well with atmospheric spectrum and agree closely with the Kolmogoroff's -2/3 law in the inertial sub-range of the spectrum. Based on the length scale of longitudinal turbulence estimated from the spectrum, a scale of 1 :900 has been proposed for laboratory modeling of environmental problems wherein the transport of mass in a neutral atmospheric surface layer IS solely due to eddies of mechanical origin.