物理
各向同性
Péclet编号
机械
不稳定性
杰纳斯粒子
经典力学
粒子(生态学)
平流
磁层粒子运动
各向异性
杰纳斯
光学
热力学
纳米技术
量子力学
地质学
磁场
海洋学
材料科学
作者
Sébastien Michelin,Eric Lauga,Denis Bartolo
出处
期刊:Physics of Fluids
[American Institute of Physics]
日期:2012-11-29
卷期号:25 (6): 061701-061701
被引量:149
摘要
Suspended colloidal particles interacting chemically with a solute are able to self-propel by autophoretic motion when they are asymmetrically patterned (Janus colloids). Here we demonstrate that the chemical anisotropy is not a necessary condition to achieve locomotion. The non linear interplay between surface osmotic flows and solute advection can produce spontaneous, and self-sustained motion of isotropic particles. We solve, for a spherical particle, the classical nonlinear autophoretic theoretical framework at arbitrary P\'eclet number. For a given set of material parameters, there exists a critical particle size, or equivalently a critical Peclet number, above which spontaneous autophoretic motion occurs. The flow induced by the particle further displays a hierarchy of instabilities associated with quantized critical Peclet numbers. Using numerical solutions of the full (unsteady) diffusiophoretic problem we confirm our analytical predictions and show that, above the instability threshold, the isotropic particles reach a steady swimming state with broken front-back symmetry in the concentration field and the hydrodynamic signature of a "pusher" swimmer. This instability to propulsion could be relevant to the high-throughput production of self-propelled particles.
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