Sound radiation from a cylindrical shell in an underwater waveguide

Sound radiation from cylindrical structures immersed in an underwater acoustic waveguide, that is, a fluid layer with an upper free surface and lower rigid floor, is a challenging engineering problem to analyze due to the complex interaction of the radiation from the excited structure and its subsequent propagation within an acoustic waveguide. To contribute to the understanding of this phenomenon, an analytical model is presented. The model involves an infinitely-long three-dimensional cylindrical shell that is point-excited and submerged in a perfect underwater waveguide, where the reflections off the free surface and rigid floor have no absorption. The equations of motion of the shell are given by thin shell theory with heavy fluid loading. The image-source method is applied directly to the acoustic boundary conditions to account for the vibroacoustic coupling of the shell and waveguide. Together, these techniques combine into an analytical framework that can evaluate both the vibration of the shell and its acoustic radiation. Results include the far-field radiated sound pressure with observations of the relative and combined effect of the waveguide boundaries.