Wan, Q: Beam Vibration Induced Acoustic Streaming

The purpose of this research is to investigate the beam vibration induced acoustic streaming. Analytical results show that the beam vibrating in standing waveforms scatters the acoustic waves into the free space with a larger attenuation coefficient and longer propagating traveling wavelength than those of the plane wave. In contrast to a constant Reynolds stress in the plane wave, the Reynolds stress generated by such acoustic wave is expected to drive the free space streaming away from the anti-nodes and towards nodes of the standing wave vibration. The sonic and ultrasonic streamings within the channel between the vibrating beam and a parallel stationary beam are also investigated. The sonic streaming is found to be mainly the boundary layer streaming dominating the whole channel while the ultrasonic streaming is clearly composed of two boundary layer streamings near both beams and a core region streaming, which is driven by the streaming velocity at the edge of the boundary layer near the vibrating beam. The acoustic streaming cooling effect is analyzed. The hysteresis and driven cavity phenomena are explored with discovery of interesting interactions among the primary eddies.