微尺度空泡溃灭驱使微球运动的机理研究  

Mechanism of the motion of spherical microparticle induced by a collapsed microbubble

作　　者：魏梦举 陈力[1] 伍涛[1] 张鸿雁[1] 崔海航[1] 

机构地区：[1]西安建筑科技大学环境与市政工程学院,西安710055

出　　处：《物理学报》2017年第16期164-172,共9页Acta Physica Sinica

基　　金：国家自然科学基金应急管理项目(批准号:11447133);国家自然科学基金青年基金(批准号:11602187);陕西省自然科学基础研究计划青年人才项目(批准号:2016JQ1008);陕西省教育厅专项科研计划(批准号:15JK1385);西部绿色建筑国家重点实验室培育基地自主科研项目资助的课题~~

摘　　要：受限空泡的溃灭是气泡动力学的核心问题,研究表明毫米尺度的空泡溃灭可以拉动附近同尺度的悬浮颗粒运动.本文针对受限空泡溃灭在微尺度下的行为开展研究,通过气泡驱动的球形微马达实验,给出了微气泡溃灭形成射流从而显著推动马达前进的现象,但由于溃灭时间很短,Micro PIV系统不能给出足够的流动细节.进而采用基于流体体积的数值手段模拟了这一过程,获得了流场的时空分布,并通过积分估算了微球获得的冲量,给出了微球所能达到的速度.结果表明这一问题与尺度密切相关,微尺度下空泡溃灭足以推动微球显著运动,在气泡尺寸固定的情况下,微球半径越小,微球与气泡间距离越近,推动的效果越明显.冲量定理则定性地解释了宏观尺度与微尺度下存在差异的原因.这一特殊的微流动问题不但扩展了空化研究的尺度范围,揭示了微尺度下空泡与颗粒作用的特性,而且对提高微马达的驱动效率也具有重要意义.Collapse of a confined bubble is the core problem of bubble dynamics. The recent study has shown that the collapse of macroscopic bubble may drive the motion of suspended particle with the similar size, but, there has still been a lack of the relevant study on a microscale. In the experiment about the bubble driven micro-motor, the locomotion of motor pushed by microjetting has been noticed. However, due to the limitation of experimental conditions, it is difficult to reveal the details of propulsion mechanism. In this paper, the volume of fluid based numerical method is adopted to simulate the interaction process between a collapsing microbubble and the suspended particle nearby. The spatial distribution and the time evolution of flow field are obtained, and the velocity that the micromotor could be achieved is deduced by integrating the impulsive force. The results show that when the bubble size is fixed, the interaction force is inversely proportional to the size of microparticle and the gap between microparticle and bubble. The Kelvin impulse theorem is used to clarify the difference between the interaction on a macroscopic scale and that on a microscopic scale. This study not only extends the scope of cavitation dynamics, which reveals the characteristics of interaction between bubble and particle on a microscale, but also is significant for improving the efficiency of self-propelled micro-motor.

关 键 词：空泡溃灭 微马达 流体体积 微流动 

分 类 号：O35[理学—流体力学]