抄録
The characteristics of turbulent particle diffusion were investigated in an atmospheric like turbulence field generated by an active-grid installed to in a small wind tunnel. Instantaneous visualization image analysis was conducted on the plume's meandering motion using a digital camera for a wide range of turbulent Reynolds number R_λ. To clarify the characteristics of the meandering plume's diffusion parameter, relative diffusion, meandering diffusion and total diffusion, were obtained by extracting the brightness values from a large number of instantaneous plume image pictures. Each diffusion parameters develops in the downstream with increase of R_λ, but their increasing tendency are vary greatly depending on dominated by either relative diffusion or meandering diffusion. The contribution rate of the relative and the meandering diffusion to the total diffusion was clarified, and these parameters are reasonable agreement with Lee & Stone's model which estimated Lagrangian properties obtained by applying the variance of total diffusion to the Taylor's theorem.
