液滴作用下小型昆虫被动运动的界面效应及流固耦合特性研究

We investigate in this project the passive movement of small insects upon the drop impact, using theoretical analysis, numerical simulation and experiments, with the aim of understanding the interface effect, fluid-structure interaction and related fluid mechanisms. The objectives of this research are: 1) to establish multiphase flow modeling that allows for multiple objects, movement of multi-degree freedom, moving contact lines and fluid-structure interaction; 2) Taking ellipse and rectangle as the typical shapes of insects, we will reveal the response of the insect motion upon impact, quantify the effects of the shapes and wettability of the object, the surface tension and inertia of the drop and other parameters on the dynamics of the impact, discuss the moment exchange between the objects and the multiphase flows, and determine the critical conditions for the transition between the movement modes. The results are expected to help the fundamental understanding of the survival of the little insects under the drop impact in nature, and to provide theoretical and technical support for the relevant engineering applications in practice, such as the design of micro-robots.

针对小型昆虫在液滴撞击作用下的被动运动，以理论分析、数值模拟和实验测试相结合为研究手段，研究其动力学过程的界面效应、流固耦合特性以及所蕴含的流动机理。研究内容包括：1) 建立具有多物体、多自由度运动、移动接触线及流固耦合的多相流物理模型，实现生物运动、界面演化及多相流动相互作用的可靠计算；2) 以椭圆体和长方体为典型昆虫形态，揭示液滴撞击过程的生物运动响应，量化生物体几何外形、浸润特性、表面张力及液滴惯性等参数对撞击动力学过程的影响，探讨生物体与多相流体之间的动量交换机制和生物运动模态转换的临界条件；既从力学角度帮助理解自然界昆虫等小型昆虫体能够在雨滴撞击下生存的科学问题，也为微型机器人设计等工程问题提供理论分析和技术支持。

针对小型昆虫在液滴撞击作用下的被动运动，建立了多物体、六自由度运动和移动接触线的多相流物理模型，结合浸没边界法和任意拉格朗日欧拉耦合算法，发展了具有动态润湿、接触角迟滞和流固耦合的三维数值模拟方法，与实验结果的对比验证了方法的可靠性和准确性，实现了生物运动、界面演化及多相流动相互作用的可靠计算；以数值模拟和理论分析为主，并结合一定实验测试，系统地研究了界面流动中曲面效应和流固耦合特性，揭示了颗粒与撞击所产生的水波之间相互作用的力学机制，给出了浸润特性、尺寸效应与界面捕获颗粒时临界撞击速度之间的尺度率关系，为微型机器人设计等工程问题提供理论分析和技术支持。