发表机构
University of Birmingham; CNRS; Ecole Polytechnique; Institut Polytechnique de Paris（伯明翰大学; 法国国家科学研究中心; 巴黎综合理工学院; 巴黎理工学院）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究通过理论分析化学活性粘性液滴沿刚性壁面的平动，发现低粘度液滴更靠近壁面且游动更快，并证明其速度对迁移率比依赖较弱，为扩散泳粒子模型的有效性提供了定量依据。
AI 中文摘要
化学活性液滴会释放化学溶质，其浓度梯度引起界面流动，进而平流输送所释放的溶质。溶质分布与流体流动之间的这种非线性耦合，使得当系统的佩克莱数Pe（即平流输运与扩散输运之比）大于有限阈值时，液滴通过平流不稳定性而自发游动。理论分析通常将活性液滴建模为扩散泳驱动的活性粒子，主要是为了简化液滴表面边界条件的实施。然而，依赖这种简化所获得的关于液滴运动的物理见解，其适用性可能受限，尤其是当液滴与其环境发生化学-流体动力学相互作用时。为此，我们在此研究化学活性粘性液滴平行于刚性壁面的平动，作为常见实验构型的一个实例。我们考虑一种推进机制，其中液滴由于界面马兰戈尼应力和扩散泳流而游动，并将我们的结果与“各向同性活性粒子”模型的结果进行比较，以检验后者的有效性。我们的分析表明，在相同的约束力下，粘度较低的液滴比粘度较高的液滴游动得更靠近壁面。这导致更快的游动，因为驱动液滴运动的浓度梯度更强。还表明，对于中等Pe，液滴的游动速度对其迁移率比（扩散泳流与马兰戈尼流的相对强度）的依赖性较弱。这种弱依赖性为研究扩散泳驱动的活性粒子以推断马兰戈尼应力驱动的活性液滴的运动提供了定量依据。
英文摘要
Chemically active drops release a chemical solute, gradients in whose concentration cause interfacial flows that advect the emitted solute. This non-linear coupling between solute distribution and fluid flow causes the drop to swim via an advective instability, if the system's Peclet number Pe--ratio of advective-to-diffusive solute transport--is larger than a finite threshold. Theoretical analyses often model active drops as diffusiophoresis-driven active particles, primarily to simplify the implementation of boundary conditions at the drop surface. However, physical insights about drop motion that rely on this simplification risk having limited applicability to fluid drops, especially when the drop is interacting chemo-hydrodynamically with its environment. Towards this, we study here the translation of a chemically active viscous drop parallel to a rigid wall, as an example of a common experimental configuration. We consider a propulsion mechanism where the drop swims due to interfacial Marangoni stresses and diffusiophoretic flows, and compare our results to those of the ''isotropic active particle'' model, to examine the validity of the latter. Our analysis shows that, for the same confining force, a less viscous drop swims closer to the wall than a more viscous drop. This results in faster swimming, due to stronger concentration gradients driving the drop's motion. It is also shown that for moderate Pe, the swimming speed of the drop depends weakly on its mobility ratio (relative strength of diffusiophoretic and Marangoni flows). This weak dependence provides a quantitative justification for studying diffusiophoresis-driven active particles to infer the motion of Marangoni-stress-driven active drops.
Commentsto appear in J. Fluid Mech., 23 pages, 15 figures, supplementary information (separate pdf)
