The dynamics of active colloids is very sensitive to the presence of boundaries and interfaces which therefore can be used to control their motion. Here we analyze the dynamics of active colloids adsorbed at a fluid–fluid interface. By using a mesoscopic numerical approach which relies on an approximated numerical solution of the Navier–Stokes equation, we show that when adsorbed at a fluid interface, an active colloid experiences a net torque even in the absence of a viscosity contrast between the two adjacent fluids. In particular, we study the dependence of this torque on the contact angle of the colloid with the fluid–fluid interface and on its surface properties. We rationalize our results via an approximate approach which accounts for the appearance of a local friction coefficient. By providing insight into the dynamics of active colloids adsorbed at fluid interfaces, our results are relevant for two-dimensional self assembly and emulsion stabilization by means of active colloids.

中文翻译：

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界面自扩散荧光胶体的数值模拟

活性胶体的动力学对边界和界面的存在非常敏感，因此可以用来控制其运动。在这里，我们分析了吸附在流体-流体界面上的活性胶体的动力学。通过使用介观的数值方法，该方法依赖于Navier–Stokes方程的近似数值解，我们表明，当吸附在流体界面时，即使两个相邻流体之间没有粘度对比，活性胶体也会经历净转矩。特别是，我们研究了该扭矩对胶体与流体-流体界面的接触角及其表面性质的依赖性。我们通过以下方式合理化我们的结果一种考虑局部摩擦系数出现的近似方法。通过深入了解吸附在流体界面上的活性胶体的动力学，我们的结果与二维自组装和借助活性胶体的乳液稳定化有关。