Hydrodynamic impulse generated by slender bodies in viscous flow

Abstract

The forces and moments on slender axisymetric bodies are studied using a hydrodynamic impulse formulation for viscous flow in non-inertial body frames of reference. The problems of steady translation and steady turning are specifically addressed. A computational fluid dynamics data base is used to evaluate the hydrodynamic impulse for 3 submarine shaped bodies with slenderness ratios of 7.35, 8.38, and 8.75. It was found that the forces and moments calculated using the hydrodynamic impulse formulation give equivalent forces and moment to the traditional method of integrating pressure and shear stress on the body. In addition, it is shown that the lateral force distribution can be calculated directly from the Lamb vector distribution over cross sectional planes. Linearized forms of the hydrodynamic impulse equations are derived for both translation and steady rotation.