Chu, P. C., Fan, C. W., & Gefken, P. R. (2008). Semi-empirical formulas of drag/lift coefficients for high-speed rigid body maneuvering in water column. Adv. Fluid Mech, 7, 163-172.
Falling of rigid body through water column with high speed is investigated experimentally and theoretically. Several experiments were conducted to shoot rigid bodies with the density ratio higher than 1 into the hydrographical tank. During the experiments, we carefully observe the position and orientation of the bomb-like rigid bodies. Using the experimental data a semi-empirical formulas for the drag/lift coefficients were obtained. With the given drag/lift coefficients, the momentum and moment of momentum equations of a fast-moving rigid body can be integrated numerically. The numerical results are well compared by the experimental data. Keywords: body-flow interaction, bomb manoeuvring, body trajectory and orientation, drag/lift coefficients, inverse modeling, bomb drop experiments. 1 Introduction Study on falling rigid body through water column with high water entry speed has wide scientific significance and technical application. Scientific studies involve nonlinear dynamics, body and multi-phase fluid interaction, supercavitation, bubble dynamics, and instability theory. Technical application of the hydrodynamics of a rigid body moving fast in fluids includes aeronautics, navigation, and civil engineering. The rigid-body dynamics allows one to set up six nonlinear equations for the most general motion (Chu et al., 2004, 2005a, b): three momentum equations and
Keywords: body-flow interaction, bomb manoeuvring, body trajectory and orientation, drag/lift coefficients, inverse modeling, bomb drop experiments.