Experimental evidence of the importance of rebound in net deposition of particles

Abstract

Experiments were carried out in a low-speed wind tunnel to examine the processes of ideal deposition, net deposition, rebound, and reentrainment for large particles (lycopodium spores and ragweed pollen) using leaf surfaces (American elm and tulip poplar). Ideal deposition velocity was found to be linearly proportional to wind speed above a threshold level; below this level it was approximately the settling velocity. Net deposition velocity was close to the ideal deposition velocity at low speeds, but at higher speeds became significantly less than ideal deposition velocity because of rebound and reentrainment. Rebound appears to be more important than reentrainment at speeds above 3 m/s, but at low speeds reentrainment may be more important than rebound, although weak. Department of Land, Air and Water Resources, University of California, Davis, CA 95616. © 1992 Elsevier Science Publishing Co., Inc.