Author(s)

P. C. Chu & G. Ray

Abstract

Falling of rigid body through air, water, and sediment with high speed is investigated experimentally and theoretically. Several experiments were conducted to shoot bomb-like rigid bodies with the density ratio similar to MK- 84 into the hydrographical tank. During the experiments, we carefully observe the position and orientation of the bomb-like rigid bodies. The theoretical work includes the development of 3D model for predicting high speed rigid body manoeuvring in air-water-sediment columns (STRIKE35) which contains three components: triple coordinate transform, hydrodynamics of falling rigid object in a single medium (air, water, or sediment) and in multiple media (air-water and water-sediment interfaces). The model predicts the rigid body’s trajectory in the water column and burial depth and orientation in the sediment. Keywords: body-flow interaction, bomb manoeuvring. 1 Introduction Study on falling rigid body through air, water, and sediment with high water entry speed has wide scientific significance and technical application. The dynamics of a rigid body allows one to set up six nonlinear equations for the most general motion: three momentum equations and three moment-ofmomentum equations. The scientific studies of the geotechnical characteristics of a rigid body in water and sediment involve nonlinear dynamics, body and multiphase fluid interaction, body-sediment interaction, supercavitation, and instability theory. The technical application of the hydrodynamics of a rigid body with high speed into fluid and non-fluid includes aeronautics, navigation, and civil

Keywords

body-flow interaction, bomb manoeuvring.