Vibrationally Driven Motion of Active Granular Particles

活动物质的相行为，如游泳的细菌，成群的动物甚至人类，目前吸引了软物质物理学的巨大兴趣。许多实验和数值研究也集中在活性胶体颗粒的行为，这通常是由当地的化学梯度驱动。在这些系统中，特别是当活性颗粒具有复杂的形状时，可以观察到各种各样的新特性。本研究项目将研究任意形状的活性颗粒的大系统。我们的系统是基于一种新颖的设计，其中粒子被构造成具有倾斜的腿，以这样一种方式，通过垂直振动激发粒子，它们在腿角度给定的方向上进行定向运动，或者通过将腿排列在一个圆中，围绕圆心主动旋转。我们期望在多粒子系统中形成各种非平衡结构和图案，例如在活性胶体的研究中观察到的和通过模拟预测的。特别是，这是一个令人着迷的问题，活跃粒子的集体运动是否主要取决于物理机制，或者是否需要个人的“智能”行为。将研究颗粒形状、运动方向、旋转方向和多分散性对集体相行为的作用。本建议书涵盖了项目前两年的工作计划，总工期为6年。

The phase behavior of active matter, such as swimming bacteria, flocks of animals or even humans currently attracts huge interest in soft-matter physics. Many experimental and numerical studies also focus on the behavior of active colloidal particles, which are typically driven by a local chemical gradient. In these systems, in particular when the active particles have a complex shape, a huge variety of novel features is observed.In this research project large systems of arbitrarily shaped active granular particles will be studied. Our system is based on a novel design, where particles are constructed with tilted legs in such a way, that by exciting the particles by vertical vibrations, they perform a directed motion in the direction given by the leg angle or, by aligning the legs in a circle, active rotation around the circle center.We expect a variety of non-equilibrium structure and pattern formation in many-particle system, such as observed in studies of active colloids and predicted in by simulations. In particular it is a fascinating question, whether collective motion of active particles depends mostly on physical mechanisms or whether ``intelligent'' behavior of individuals is required. The role of particle shape, direction of motion, sense of rotation and polydispersity on the collective phase behavior will be investigated. This proposal covers the work program for the first 2 years of project aiming for a total duration of 6 years.