自驱动Janus微球分数布朗运动的颗粒动力学模拟

Particle dynamics simulation on fractional Brownian motion of self-propellant Janus microsphere

该文通过分析Janus微球的运动过程,建立了包括随机布朗力、布朗力矩、自驱动力及Stokes阻力在内的颗粒动力学模型,通过数值模拟手段研究了不同粒径和不同自驱动速度下Janus微球的分数布朗运动,获得了不同的运动模式、均方位移及Hurst指数。模拟结果表明,Janus微球的均方位移随时间非线性增加,在不同观察时间下Janus微球可呈现出布朗运动、自驱动及类布朗运动的特征,Hurst指数亦产生相应变化。数值模拟结果与实验结果很好地符合,反映出Janus微球的分数布朗运动特性,说明所建颗粒力学模型的合理性,为今后Janus微球的操控与具体应用奠定了基础。

Based on Janus microsphere＇s motion analysis, the particle dynamic model involving random Brownian force and toque, self-propulsion and Stokes drag are constructed. Through numerical solving, the effect of different diameters and different self-propulsion strength on fractional Brownian motion are studied. Different motion modes and the mean square displacement 〈△L2〉 and Hurst indexes are obtained. The simulation results show that 〈 △L2〉 increases with At nonlinearly, Janus particle may be characteriged as the Brownian motion, self-propulsion and Brownian-like motion under the different At and Hurst indexes also change correspondingly. Numerical simulation and experimental observation are in good agreement, which proves the present model reasonable and also provides the foundation for the followed manipulation of Janus particle and the practice applications.