An equivalent source CVIS method and its application in predicting structural vibration and acoustic radiation in ocean acoustic channe

Abstract

The acoustic wave propagating in ocean is severely distorted due to the sound speed profile of sea water and the reflection and absorption of seabed. The FEM/BEM is a preferable method to solve the fluid-structure interactive vibration and sound radiation problem of underwater structure in ocean acoustic environment, since the Green function can be applied in the integral equation. The simple source integral method is more preferable compared with Helmholtz integral because the calculation of normal derivative of Green function is avoided. In order to remove the irregular frequency problem, Zhou (Zhou et al., 2010) proposed a CVIS theory, which however introduced the normal derivative of Green function on CVIS surface and limited its application into ocean acoustical environment. Therefore, an equivalent source formulation of CVIS is proposed based on the definition of normal derivative so that the normal derivative of Green function on the integration of CVIS is replaced. The radiated SPL of spherical shell is calculated in shallow and deep sea with various sound speed profiles. It is shown that the equivalent source CVIS can be used to eliminate the irregular frequency problem of the far field radiated sound pressure of underwater elastic structure in ocean acoustic environment.