School of Mathematics, University of Bristol, Clifton, Bristol BS8 1TW, United Kingdom.
School of Mathematics, University of Bristol, Clifton, Bristol BS8 1TW, United Kingdom and Isaac Newton Institute for Mathematical Sciences, Cambridge CB3 0EH, United Kingdom.
Phys Rev Lett. 2014 Apr 11;112(14):148104. doi: 10.1103/PhysRevLett.112.148104.
We introduce a phenomenological theory for a new class of soft active fluids with the ability to synchronize. Our theoretical framework describes the macroscopic behavior of a collection of interacting anisotropic elements with cyclic internal dynamics and a periodic phase variable. This system can (i) spontaneously undergo a transition to a state with macroscopic orientational order, with the elements aligned, a liquid crystal, (ii) attain another broken symmetry state characterized by synchronization of their phase variables, or (iii) a combination of both types of order. We derive the equations describing a spatially homogeneous system and also study the hydrodynamic fluctuations of the soft modes in some of the ordered states. We find that synchronization can promote or inhibit the transition to a state with orientational order, and vice versa. We provide an explicit microscopic realization: a suspension of microswimmers driven by cyclic strokes.
我们介绍了一种新的软活性流体的唯象理论，这类流体具有同步的能力。我们的理论框架描述了由具有循环内动力学和周期性相位变量的各向异性元素相互作用组成的集合的宏观行为。该系统可以 (i) 自发地经历一个向宏观各向有序的状态转变，其中元素对齐，形成液晶；(ii) 达到另一个具有相位变量同步的对称性破缺状态；或 (iii) 两种类型的有序状态的组合。我们推导出了描述空间均匀系统的方程，并研究了一些有序态中软模式的流体力学涨落。我们发现，同步可以促进或抑制向具有各向有序的状态转变，反之亦然。我们提供了一个明确的微观实现：由周期性冲程驱动的微泳者悬浮液。
