论文信息 - IN THE PRESENCE OF A GRADIENT IN TURBULENT-VELOCI TY VARIANCE

IN THE PRESENCE OF A GRADIENT IN TURBULENT-VELOCI TY VARIANCE

Recent papers by Wilson etal. (1981b) and Legg and Raupach (1982) give methods for the calculation of particle trajectories in turbulence with a gradient in vertical velocity variance a2w . However the two methods seem contradictory. This paper demonstrates that in systems in which l(da~/dz) (where l is the length scale) varies only slowly with height z, the two methods give similar predictions, and indicates why this is the case. For a particular system in which the restriction on l(dtrw/dz ) is not satisfied, it is shown that neither method is correct but that a simple modification of the method of Wilson et aL (198 l b) gives reasonable predictions.

D. Thomson | John D. Wilson | B. Legg

[1] B. J. Legg,et al. Turbulent dispersion from an elevated line source: Markov chain simulations of concentration and flux profiles , 1983 .

[2] M. Raupach,et al. Markov-chain simulation of particle dispersion in inhomogeneous flows: The mean drift velocity induced by a gradient in Eulerian velocity variance , 1982 .

[3] John D. Wilson. Turbulent dispersion in the atmospheric surface layer , 1982 .

[4] G. W. Thurtell,et al. Numerical simulation of particle trajectories in inhomogeneous turbulence, III: Comparison of predictions with experimental data for the atmospheric surface layer , 1981 .

[5] G. W. Thurtell,et al. Numerical simulation of particle trajectories in inhomogeneous turbulence, I: Systems with constant turbulent velocity scale , 1981 .

[6] John D. Reid. Markov Chain Simulations of Vertical Dispersion in the Neutral Surface Layer for Surface and Elevated Releases , 1979 .

[7] Geoffrey Ingram Taylor,et al. Diffusion by Continuous Movements , 1922 .