Experimental Simulation of Atmospheric Diffusion : 1st Report, On the Features of the Large-Scale Turbulence Field and Mean Concentration distribution

Abstract

Particle diffusion from a point source was experimentally investigated in a homogeneous and quasi-isotropic large-scale turbulence field. The particle concentration was measured by a laser counting system. The flow visualization showed the meandering of a particle plume and the diffusion coefficient reached about 130cm²/sec in the strong turbulence. The plume dispersed downstream in proporti on to t in the strong turbulence and to t^1/2 in the weak turbulence. The results were well desctibed by the Taylor's theory. The empirical relation for the plume spread as a function of the travel time assured that the turbulence generator made it possible to simulate the atmospheric diffusion in a wind tunnel with conventional size.