摘要
Janus颗粒的自驱动力研究对于纳微米尺度驱动力课题具有重要意义,本文针对Pt-SiO_2型Janus颗粒,基于格子Boltzmann模型及动量交换法提出了计算其扩散泳力的方法,通过与实验数据对比修正验证了模型准确性,并通过分析证明了此类Janus颗粒的扩散泳力与速度场无关,进一步模拟比较了不同形状颗粒的自驱运动.分析发现,对于体积相等形状不同的Janus颗粒,扩散泳力主要由轴线投影面积决定,此外反应面积也会对扩散泳力产生影响.
Studies of the driving force of the self-propulsion Janus particles are very important in the fields of micro-power and nano-motor.In this paper,we choose the micron Pt-SiO2-type Janus particle as a research object,which is propelled by self-generated concentration gradient in the dilute solution of H2O2,focusing on the self-propulsion of the single particle.According to the force analysis of the Janus particle,the surface force can be decomposed into the viscous resistance of the fluid,the Brownian force derived from the molecular thermal fluctuation,and the diffusiophoresis caused by the diffusion of the solute component.The main aim of this paper is to find the way to accurately simulate the diffusiophoresis generated by the huge concentration gradient on a microscale.The lattice Boltzmann method（LBM） is a modern mesoscopic method based on the microscopic particle characteristics of the fluid,which makes it more intuitive to deal with the interaction between the fluid and solid.It is more advantageous than the traditional numerical method in the description of this micro-interface dynamic problem,i.e.,the self-propulsion of Janus particle.On a certain time scale,when the Janus particle shows the directional motion,the influence of the Brownian force can be ignored.Thus,the analytical process can be simplified.Based on the momentum theorem,the method of calculating the diffusiophoresis produced by concentration diffusion is proposed.We introduce the momentum exchange in the half-way bounce-back scheme of LBM into the model of the multicomponent diffusion and reaction.Through counting the surface force we can obtain the diffusiophoresis acting on the Janus particle.Moreover,this diffusiophoresis model is modified by comparing the experimental fluid resistance with simulated one.This comparision verifies the validity of the diffusiophoresis model.Then,the analysis of the variation of diffusiophoresis proves that the value of diffusiophoresis is independent of the fluid velocity.Through the further application
出处
《物理学报》
SCIE
EI
CAS
CSCD
北大核心
2017年第8期189-198,共10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科学基金(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~~
