Manghi Manoel, Schlagberger Xaver, Kim Yong-Woon, Netz Roland R
Laboratoire de Physique Théorique, IRSAMC, Université Paul Sabatier, 31062, Toulouse, France.
Physik Department, Technical University Munich, 85748, Garching, Germany.
Soft Matter. 2006 Jul 20;2(8):653-668. doi: 10.1039/b516777a.
Recent theoretical works exploring the hydrodynamics of soft material in non-equilibrium situations are reviewed. We discuss the role of hydrodynamic interactions for three different systems: (i) the deformation and orientation of sedimenting semiflexible polymers, (ii) the propulsion and force-rectification with a nano-machine realized by a rotating elastic rod, and (iii) the deformation of a brush made of grafted semiflexible polymers in shear flow. In all these examples deformable polymers are subject to various hydrodynamic flows and hydrodynamic interactions. Perfect stiff nano-cylinders are known to show no orientational effects as they sediment through a viscous fluid, but it is the coupling between elasticity and hydrodynamic torques that leads to an orientation perpendicular to the direction of sedimentation. Likewise, a rotating stiff rod does not lead to a net propulsion in the Stokes limit, but if bending is allowed an effective thrust develops whose strength and direction is independent of the sense of rotation and thus acts as a rectification device. Lastly, surface-anchored polymers are deformed by shear flows, which modifies the effective hydrodynamic boundary condition in a non-linear fashion. All these results are obtained with hydrodynamic Brownian dynamics simulation techniques, as appropriate for dilute systems. Scaling analyses are presented when possible. The common theme is the interaction between elasticity of soft matter and hydrodynamics, which can lead to qualitatively new effects.
本文综述了近期探索非平衡状态下软物质流体动力学的理论研究工作。我们讨论了流体动力学相互作用在三种不同系统中的作用：（i）沉降半柔性聚合物的变形和取向；（ii）由旋转弹性杆实现的纳米机器的推进和力整流；（iii）接枝半柔性聚合物刷在剪切流中的变形。在所有这些例子中，可变形聚合物都受到各种流体动力学流动和流体动力学相互作用的影响。已知完美的刚性纳米圆柱体在通过粘性流体沉降时不会表现出取向效应，但正是弹性和流体动力学扭矩之间的耦合导致了垂直于沉降方向的取向。同样，在斯托克斯极限下，旋转的刚性杆不会产生净推进力，但如果允许弯曲，则会产生有效的推力，其强度和方向与旋转方向无关，因此可作为整流装置。最后，表面锚定的聚合物会因剪切流而变形，这会以非线性方式改变有效的流体动力学边界条件。所有这些结果都是通过适用于稀溶液系统的流体动力学布朗动力学模拟技术获得的。在可能的情况下进行了标度分析。共同的主题是软物质弹性与流体动力学之间的相互作用，这可能会导致定性的新效应。
