The acoustic power from moving and pulsating spheres

Two related matters are dealt with this paper: one involves a general and broadly applicable quantitative description (employing linear theory) of the acoustical power radiated from individual or superposed point sources in arbitrary subsonic motion through a quiescent fluid and the other concerns the power estimate, directly obtained thereby, which pertains to a sphere moving rectilinearly at low, but variable, speeds. A concurrent variation in the sphere radius is also taken into account and specific examples of such prescribed motions are detailed. Known results, based on a small perturbation or linear approximation, are recovered and the formulation developed enables systematic refinements, outside the scope of linear theory, to be found.