J2.8
The influence of Lagrangian time scales on canopy diffusion
M. Y. Leclerc, University of Georgia, Griffin, GA; and T. V. Prabha
Lagrangian dispersion modeling of turbulent processes requires the information on Lagrangian characteristics of turbulence such as wind velocity variances and Lagrangian time scales. In spite of its paramount importance, the Lagrangian time scale turbulence characteristic has been poorly quantified in large part because of the paucity of experimental data arising from the difficulties inherent in such measurements.This difficulty is compounded even further in the case of canopy turbulent diffusion where traditionally the few experimental techniques used to determine the Lagrangian timescale are not directly applicable due to the associated inhomogeneity. Most of the observations are done in an Eulerian framework and for in-canopy flow Lagrangian measurements are available mostly from wind tunnel experiments. Large-eddy simulation (LES) may provide an alternative to describe the Lagrangian properties of the flowfield within and above canopy.Eulerian and Lagrangian time scales are derived from the LES output for a neutral case. The sensitivity of various turbulence length scale formulations is evaluated.
Joint Session 2, Dispersion (Joint with the Fourth Symp. Urban Environment, 12th Joint Conf. on the Applications of Air Pollution Meteorology with A&WMA, and 25th Conf. Agricultural & Forest Meterology)
Tuesday, 21 May 2002, 1:30 PM-4:40 PM
Previous paper Next paper