Janus颗粒在平面壁附近的自主运动：润滑极限分析

摘要

我们研究球形化学活性颗粒在平面不可渗透壁面附近的自身扩散泳行为，重点分析颗粒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颗粒（其催化活性帽内包含小型惰性区域）进行解析。虽然数值模拟已被用于研究此类颗粒，但由于几何约束和陡峭的溶质浓度梯度，在极近壁区域解析流动和输运过程存在困难。我们通过近接触极限下的渐近分析来突破这一局限，该极限下颗粒与壁面间隙极为狭窄。特别地，我们考察了惰性区域尺寸与润滑区域渐近相当的特定极限情况。通过分析惰性表面平行于壁面的轴对称构型，并将研究拓展至轻微倾斜取向。研究发现，翻转现象决定了倾斜颗粒是向轴对称状态回转还是持续重新取向，由此揭示了近接触区域内颗粒的旋转稳定性特征。

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

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