US Patent 8123502 Acoustic pump utilizing radial pressure oscillations

A fluid pump comprising one or more actuators, two end walls, a side wall; a cavity which, in use, contains fluid, the cavity having a substantially cylindrical shape bounded by the end walls and the side walls, at least two apertures through the cavity walls, at least one of which is a valved aperture, wherein the cavity radius, a, and height, h, satisfy the following inequalities: a/h is greater than 1.2; and h2/a is greater than 4×10−10 m; and wherein, in use, the actuator causes oscillatory motion of one or both end walls in a direction perpendicular to the plane of the end walls; whereby, in use, the axial oscillations of the end walls drive radial oscillations of fluid pressure in the cavity.