The Influence of Forest Canopies on the Decay of Aircraft Wake Vortices and Downwash

Abstract

Abstract. The dominant mechanism driving aerially released spray material toward the ground is the flow field generated by the aircraft, in the form of either aircraft vortices or downwash. In AGDISP, the initial strength of this flow field is reduced over time by a simple damping mechanism tied to atmospheric turbulence. When these flow fields enter a forest canopy, the scrubbing impact of the canopy structure further reduces their strength and influences the behavior of spray droplets released into the canopy. This study uses a simple model to approximate the canopy damping mechanism and then applies this model to a recent canopy dataset in an effort to validate the approach proposed. Keywords: Aerial spray, AGDISP, Aircraft vortices, Canopy penetration, Damping, Downwash.