A pump comprising: a pump body having a substantially elliptically shaped side wall closed by two end walls, and a pair of internal plates (12, 13) adjacent each other and supported by the side wall to form two cavities (16, 17) within said pump body for containing fluids, each cavity having a height (h) and a radius (r), wherein a ratio of the radius (r) to the height (h) is greater than about 1.2; an actuator formed by the internal plates wherein one of the internal plates is operatively associated with a central portion (22 or 23) of the other internal plate and adapted to cause an oscillatory motion at a frequency ( f) thereby generating radial pressure oscillations of the fluid within each of the cavities including at least one annular pressure node in response to a drive signal being applied to said actuator when in use; an isolator disposed between said actuator and the sidewall to reduce dampening of the oscillatory motion of the actuator; a first aperture extending through said actuator to enable the fluid to flow from one cavity to the other cavity, the first aperture located at approximately a centre of the actuator; a first valve disposed in said first aperture to control the flow of fluid through said first aperture; a second aperture extending through a first one of the end walls to enable the fluid to flow through the cavity adjacent the first one of the end walls, the second aperture located substantially at a centre of the first of the end walls; a second valve disposed in said second aperture to control the flow of fluid through said second aperture; and a third aperture extending through a second one of the end walls to enable the fluid to flow through the cavity adjacent the second one of the end walls, the third aperture located substantially at a centre of the second of the end walls; whereby fluids flow into one cavity and out the other cavity when in use. a pump body having a substantially elliptically shaped side wall closed by two end walls, and a pair of internal plates (12, 13) adjacent each other and supported by the side wall to form two cavities (16, 17) within said pump body for containing fluids, each cavity having a height (h) and a radius (r), wherein a ratio of the radius (r) to the height (h) is greater than about 1.2; an actuator formed by the internal plates wherein one of the internal plates is operatively associated with a central portion (22 or 23) of the other internal plate and adapted to cause an oscillatory motion at a frequency ( f) thereby generating radial pressure oscillations of the fluid within each of the cavities including at least one annular pressure node in response to a drive signal being applied to said actuator when in use; an isolator disposed between said actuator and the sidewall to reduce dampening of the oscillatory motion of the actuator; a first aperture extending through said actuator to enable the fluid to flow from one cavity to the other cavity, the first aperture located at approximately a centre of the actuator; a first valve disposed in said first aperture to control the flow of fluid through said first aperture; a second aperture extending through a first one of the end walls to enable the fluid to flow through the cavity adjacent the first one of the end walls, the second aperture located substantially at a centre of the first of the end walls; a second valve disposed in said second aperture to control the flow of fluid through said second aperture; and a third aperture extending through a second one of the end walls to enable the fluid to flow through the cavity adjacent the second one of the end walls, the third aperture located substantially at a centre of the second of the end walls; whereby fluids flow into one cavity and out the other cavity when in use.