标题： 几何依赖的剪切活性流体粘度降低 显示英文标题

标题： Geometry-dependent viscosity reduction in sheared active fluids

摘要： 我们通过研究一个广义的纳维-斯托克斯模型来探讨活性流体中的流动模式形成和粘度降低机制，该模型捕捉了微生物悬浮液中实验观察到的整体涡旋动力学。 我们提出了精确的解析解，包括无应力的涡旋晶格，并引入了一个计算框架，使得以前难以处理的高阶剪切边界条件能够被高效处理。 大规模参数扫描确定了自发流动对称性破缺、几何依赖的粘度降低以及适用于受限悬浮液中能量收集的负粘度状态的条件。 该理论仅基于对活性应力张量的对称性和长波结构的通用假设，表明通过调整受限几何形状和图案尺度选择，可能在广泛的非平衡流体中实现无粘性相。 显示英文摘要

摘要： We investigate flow pattern formation and viscosity reduction mechanisms in active fluids by studying a generalized Navier-Stokes model that captures the experimentally observed bulk vortex dynamics in microbial suspensions. We present exact analytical solutions including stress-free vortex lattices and introduce a computational framework that allows the efficient treatment of previously intractable higher-order shear boundary conditions. Large-scale parameter scans identify the conditions for spontaneous flow symmetry breaking, geometry-dependent viscosity reduction and negative-viscosity states amenable to energy harvesting in confined suspensions. The theory uses only generic assumptions about the symmetries and long-wavelength structure of active stress tensors, suggesting that inviscid phases may be achievable in a broad class of non-equilibrium fluids by tuning confinement geometry and pattern scale selection.