WIND-TUNNEL EXPERIMENT ON FLOW AND TRACER GAS-DIFFUSION IN CONVECTIVEPLANETARY BOUNDARY-LAYER

The temperature of a flat wind tunnel floor was increased almost unifo rmly to 80 degrees C to simulate an unstable atmospheric boundary laye r. The velocity, temperature and surface temperature heat flux on the wind tunnel floor were measured using a laser Doppler anemometer, a re sistance thermometer and a thin-film-type heat flowmeter. The tracer g as was released from continuous point sources located in the simulated unstable boundary layer, and its spatial concentration was measured b y flame ionization detectors. The measured turbulent flow and tracer g as concentration characteristics such as turbulence intensities and pl ume spreads showed good agreement with those obtained from field exper iments and water tank experiments when normalized by the convective ve locity. The universal functions for velocity and temperature profiles were applied and the empirical constants were optimized. The length sc ales of turbulent motion were estimated by means of the universal func tions. It appeared that the convective velocity and convective tempera ture could be applied as the similarity parameter for the flow and tra cer gas diffusion when considering the corresponding equivalent atmosp heric conditions.