Active fluids composed of constituents that are constantly driven away from thermal equilibrium can support spontaneous currents and can be engineered to have unconventional transport properties. Here, we report the emergence of (meta)stable traveling bands in computer simulations of aligning circle swimmers. These bands are different from polar flocks and, through coupling phase with mass transport, induce a bulk particle current with a component perpendicular to the propagation direction, thus giving rise to a collective Hall (or Magnus) effect. Traveling bands require sufficiently small orbits and undergo a discontinuous transition into a synchronized state with transient polar clusters for large orbital radii. Within a minimal hydrodynamic theory, we show that the bands can be understood as nondispersive soliton solutions fully accounting for the numerically observed properties.

中文翻译：

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手性活性流体中的集体霍尔电流：通过行带的相和质量传输的耦合


由不断偏离热平衡的成分组成的活性流体可以支持自发电流，并且可以被设计为具有非常规的传输特性。在这里，我们报告了在排列圆圈游泳者的计算机模拟中出现（亚）稳定行进带。这些带与极性群不同，通过与质量传输的耦合相，感应出具有垂直于传播方向的分量的体粒子电流，从而产生集体霍尔（或马格努斯）效应。行进带需要足够小的轨道，并经历不连续的过渡到具有大轨道半径的瞬态极簇的同步状态。在最小流体动力学理论中，我们表明这些能带可以理解为非色散孤子解，完全解释了数值观察到的特性。