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. The model assesses the curtain shape, the position along the curtain where flow separation occurs, the velocity of winds winnowing ejecta out of the effectively 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 model results duplicate observation of curtain shape and size of ejecta entrained. The position where flow separation occurs is duplicated when the curtain porosity is assumed to increase with time. (C) 1999 Elsevier Science Ltd. All rights reserved.