Acoustic microstreaming induced by pattern of Faraday waves on a bubble wall

Interest to acoustic microstreaming is supported by the variety of applications: micromixing, transferring lipid vesicles and large molecules in desired direction, and selective particle trapping which are essential to the success of lab-on-a-chip- devices. It is generally assumed that the main contributions to the streaming generated by a gas bubble come from the pulsation and translation modes. This study deals with the microstreaming which is induced when a bubble is driven acoustically in the regime of parametrically generation of Faraday waves. The greater wall displacement amplitude for l > 1modes means that their effect on the flux of species near the bubble wall can be much greater than that of the breathing mode. The modes with a fixed order l have a high degree of degeneracy equal to (2l+1). The choice of which modes are chosen to grow to steady state, and which are selected out, determines the shape of the perturbation and hence the structures of the streaming flow. Basic features of pattern formation on the bubble wall have been recently derived by Maksimov & Leighton (doi:10.1098/rspa.2011.0366) which provides determination of streaming structures. These theoretical findings are used to interpret the experiments on selective particle trapping by oscillating microbubble.