Diffuse radiation from submerged thin shells

The acoustic power and radiation pattern shed from diffusely vibrating thin walled submerged shells is calculated using a statistical method. At frequencies below coincidence flexural waves on smooth shells cannot efficiently radiate into the fluid. Radiation is therefore dominated by the longitudinal and shear waves, which couple to the fluid by means of curvature and the Poisson effect. Assumed equipartition of acoustic energy amongst flexural, shear and extensional modes, and eikonal approximation calculations of the radiation rate from each mode result in estimates for the diffuse radiation rates which are largely independent of details of the structure. The assumptions behind the present theory and the consequent restrictions of its applicability are examined. The potential for extension of the theory to more general conditions is discussed.