Added mass of submerged objects of arbitrary shapes

Abstract

Hydrodynamic loads induced on large underwater structures by Impulsive motion may be significant design factors. Such loads may be induced by earthquake excitation or may result from acceleration produced while lifting an object in the sea. The theoretical approach to the calculation of these loads is outlined and numerical results are presented for several submerged configurations including a vertical cone, a sphere, and a vertical circular cylinder. Numerical results for these submerged structures are presented in the form of a dimensionless load parameter or added mass coefficient. Results corresponding to a number of different water depths are presented to show the rather sizable effect of the relative water depth on the hydrodynamic force. It is shown that the effect of the free water surface is to reduce the hydrodynamic loads in comparison to the corresponding infinite depth values. Experimental results obtained by vibration testing are presented for a submerged sphere, a cone and a vertical cylinder. These results show excellent agreement with the theoretical results.