The grain-bed impact process in aeolian saltation

Abstract

We report the results of impact experiments in which high velocity steel spheres (BBs) were directed against a loose bed of similar particles. The purpose of these experiments is to shed some light on the collision processes which occur when saltating sand grains driven by the wind strike the bed. The scattered particles fall into two categories: a single high energy rebound which scatters quasi-specularly, and a number of low energy recoils. The high energy rebound is identified with the “successive saltation” particle of Rumpel, and the low energy recoils are interpreted as creeping, or reptating particles. These observations provide information on the “splash function” of Ungar and Haff, which describes the response of a bed to grain impact and which plays a central role in the theory of saltation.