I. Acoustic radiation and reflection from spheres. II. Some effects of thermal conduction and compressibility in the collapse of a spherical bubble in a liquid

This thesis presents the results of computations for four problems: two in the field of acoustics and two on the collapse of a cavity in a liquid. The first is an analysis of echoes from a solid homogeneous sphere in water, and demonstrates that the vibrations induced in the solid material by incident sound waves have an important effect on the form of the echo. Various materials are examined and the theory is shown to provide a satisfactory explanation for echoes observed in sonar work. The second problem deals with the far-field radiation patterns formed by different types of source distributions on the surface of a rigid sphere, and demonstrates the effect of the shape of a transducer and its housing on such radiation patterns. The problem of the binaural localization of sound sources is also considered. The third problem is concerned with the behavior of a thermally conducting gas inside a collapsing cavity in a liquid. It is shown that, for bubbles of an appropriate size, thermal conduction in the gas can account for the varying intensities of sonoluminescence which have been observed when different gases are dissolved in water. In the final problem, the shock waves which form in the liquid as a result of a cavity collapse are investigated. It is estimated that such shock waves could be a potent cause of cavitation damage