Janus颗粒在平面壁附近的自主运动：润滑极限分析

摘要

我们研究了球形化学活性粒子在不可渗透平面壁附近的自身扩散泳运动，重点分析了粒子取向对推进作用的影响。针对具有不对称表面化学活性的Janus粒子（其催化活性帽内包含小型惰性区域）进行了理论解析。尽管数值模拟已被用于研究此类粒子，但由于几何约束和陡峭的溶质浓度梯度，在极近壁区域求解流动和输运过程仍存在困难。我们通过近接触极限（粒子与壁面间隙极小）下的渐近分析解决了这一局限，特别考察了惰性区域尺寸与润滑区域渐近相当的特定情形。通过分析惰性表面平行于壁面的轴对称构型，并将研究拓展至微倾斜取向，发现翻转现象决定了倾斜粒子是向轴对称状态回转还是持续转向，从而表征了近接触区域内粒子的旋转稳定性。

English

We study the self-diffusiophoresis of a spherical chemically active particle near a planar, impermeable wall, with a focus on the influence of particle orientation on propulsion. We analyze a Janus particle with asymmetric surface chemical activity, consisting of a small inert region within a catalytically active cap. While numerical simulations have been used to study such particles, they encounter difficulties resolving the flow and transport in the extreme near-wall regime due to geometric confinement and steep solute concentration gradients. We address this limitation through an asymptotic analysis in the near-contact limit, where the gap between the particle and the wall is narrow. In particular, we consider the distinguished limit in which the inert region is asymptotically comparable in size to the lubrication region. We analyze an axisymmetric configuration in which the inert face is oriented parallel to the wall and extend the analysis to slightly tilted orientations. We find that the capsize determines whether a tilted particle rotates back toward the axisymmetric state or continues to reorient, thereby characterizing its rotational stability in the near-contact regime.

Janus颗粒在平面壁附近的自主运动：润滑极限分析

Autophoresis of a Janus particle near a planar wall: a lubrication limit

摘要

Support