论文标题
活性引起的液滴推进和多纹理
Activity-induced droplet propulsion and multifractality
论文作者
论文摘要
我们开发了一个最小的流体动力模型，没有方向秩序参数，用于封装在二元流体乳液液滴中的收缩游泳者组合。我们的模型使用两个耦合标量订单参数，分别是$ ϕ $和$ψ$，分别捕获了该液滴中的液滴接口和收缩游泳者的活动。这些订单参数也与速度字段$ \ bm U $耦合。在低活动时，我们的模型产生了一个自我销售的液滴，其质量$（cm）$的中心显示了直线运动，该运动由场$ψ$的时空演化提供动力，这导致了液滴一端的时间依赖性涡旋偶极子。随着我们的活动增加，这种$ cm $显示了混乱的超延伸运动，我们以均方根位移为特征。液滴界面表现出多重波动，我们计算的指数频谱。我们探讨了结果对收缩游泳者活跃液滴的实验的含义。
We develop a minimal hydrodynamic model, without an orientational order parameter, for assemblies of contractile swimmers encapsulated in a droplet of a binary-fluid emulsion. Our model uses two coupled scalar order parameters, $ϕ$ and $ψ$, which capture, respectively, the droplet interface and the activity of the contractile swimmers inside this droplet. These order parameters are also coupled to the velocity field $\bm u$. At low activity, our model yields a self-propelling droplet whose center of mass $(CM)$ displays rectilinear motion, powered by the spatiotemporal evolution of the field $ψ$, which leads to a time-dependent vortex dipole at one end of the droplet. As we increase the activity, this $CM$ shows chaotic super-diffusive motion, which we characterize by its mean-square displacement; and the droplet interface exhibits multifractal fluctuations, whose spectrum of exponents we calculate. We explore the implications of our results for experiments on active droplets of contractile swimmers.
