Abstract: The simplest ?random flight? models for the paths of heavy particles in turbulence have been tested against previous observations of the deposition of glass beads from an elevated source in the atmospheric surface layer. ...

Abstract: To evaluate Reynolds-averaged Navier?Stokes (RANS) models of disturbed micrometeorological winds, steady-state computations using a second-order closure are compared with observations (see Part I) in which the surface layer ...

Abstract: In numerical weather prediction models, drag on unresolved terrain is usually represented by augmenting the boundary drag on the model atmosphere, in terms of an effective surface roughness length. But as is shown here, ...

Abstract: Wind statistics were measured using cup and sonic anemometers, placed upwind and downwind from a porous plastic windbreak fence (height h = 1.25 m, length Y = 114 m, resistance coefficient kr0 = 2.4, and porosity p = 0.45) ...

Abstract: From an analysis of scales in the cloud droplet collision problem, the authors infer that a trajectory model that is to be capable of predicting collisions between droplets of all possible sizes should be of second-order, ...

Abstract: Wind velocity statistics from several points within a regular but sparse array of clumped corn plants are analyzed, with each clump consisting of 12 plants, having a mean height of 1.6 m and a collective leaf area of about ...

Abstract: Lagrangian stochastic (LS) dispersion models often use trajectory reflection to limit the domain accessible to a particle. It is shown how the well-mixed condition (Thomson) can he expressed in the Chapman-Kolmogorov ...

Abstract: When a particle descends beneath the (nominal) lower boundary of the atmosphere, it may remain there for some time τ before it reemerges into the (resolved) flow. In particle trajectory models, τ is the random duration of ...

Abstract: Katul and Chang recently compared the performance of two second-order closure models with observations of wind and turbulence in the Duke Forest canopy, noting that such models ?alleviate some of the theoretical objections ...

Abstract: ?Backward? Lagrangian stochastic models calculate an ensemble of fluid element (particle) trajectories that are distinguished by each passing through an observation point. As shown, they can be faster and more flexible in ...