Explanation of the mechanism of the acoustic streaming for droplet micro-reactor

在声表面波（SAW）传播表面上的液滴中会发生声流现象，本研究的目的是在观测的基础上澄清液滴中的现象，并用有限元方法对这些现象进行解释。利用高速摄像机，我们成功地观察到了液滴中的声流。当液滴不被操纵时，观察到稳定的流动。当液滴被操纵时，一个声压力作用于液滴的尖端，并使其延伸。然而，液滴的SAW入射侧没有变形。当声压力大于结合力时，对液滴入射侧进行拖拽，进而对液滴进行操纵。在液滴操作过程中，液滴表面发生变化。为了模拟液滴的运动，必须考虑自由边界模型进行计算。在我们的计算方法中引入自由边界模型是困难的。这是我们未来的工作。

An acoustic streaming is occurred in a droplet on a surface acoustic wave (SAW) propagating surface The aim of this research is to clarify phenomena in the droplet based on the observations and to explain those using finite element method. Using a high-speed camera, we succeeded to observe the acoustic streaming in a droplet. When the droplet is not manipulated, stable streaming was observed. When the droplet is manipulated, an acoustic pressure force acts to the tip of it and that is extended. However, SAW incident side of droplet is not deformed. When the acoustic pressure force is larger than binding force, incident side of the droplet is dragged and then the droplet is manipulated. Droplet surface is changed during droplet manipulation. To simulate of the droplet manipulation, we must consider free boundary model for the calculation. It is difficult to introduce the free boundary model into our calculation method. This is our future work.