Interactions between an impact generated ejecta curtain and an atmosphere

A theoretical model investigates the interaction between an ejecta curtain and a variety of differing atmospheric conditions in order to determine the ejecta entrainment capacity of winds generated by an advancing curtain. Th e model assesses the curtain shape, the position along the curtain where fl ow separation occurs, the velocity of winds winnowing ejecta out of the eff ectively impermeable portions of the curtain and the velocity of winds flow separating at its top. Wind velocities allow estimating the size range of ejecta entrained. Tested against laboratory impacts into coarse sand, the m odel results duplicate observation of curtain shape and size of ejecta entr ained. The position where flow separation occurs is duplicated when the cur tain porosity is assumed to increase with time. (C) 1999 Elsevier Science L td. All rights reserved.