Numerical simulation of acoustic streaming generated by finite-amplitude resonant oscillations in an enclosure

Acoustic streaming motion in a compressible gas filled two-dimensional rectangular enclosure is simulated and the effects of the sound field intensity on the formation process of streaming structures are investigated numerically. The oscillatory flow field in the enclosure is created by the vibration of the left wall of the enclosure. The frequency of the wall vibration is chosen such that the lowest acoustic mode propagates along the enclosure. The fully compressible form of the Navier–Stokes equations is considered and an explicit time-marching algorithm is used to track the acoustic waves. The formation of the wave field in the enclosure is computed and fully described and the acoustic boundary layer development is predicted. The interaction of the wave field with viscous effects and the formation of streaming structures are revealed by time-averaging the solutions over a given period. The strength of the pressure waves associated with the acoustic effect and the resulting streaming flow pattern is found to be strongly correlated to the maximum displacement of the wall during a vibration cycle. The wave form determines the shape of the steady streaming structures in the oscillatory flow field.