The Pressure of Active Matter

CBET 1437570含有可以在液体中推进自己的粒子的悬浮液是一类称为活性物质的材料的有趣例子。 自推进颗粒，有时被认为是游泳者，可以对悬浮液的整体性质做出贡献。 这个项目将探索一个新的概念，称为游泳压力，可以帮助描述这种暂停的状态。游动压力类似于气体中的分子施加在容器壁上的通常压力，但在这种情况下，压力是由自推进颗粒施加的，这些颗粒可以是微生物，化学反应颗粒或在液体中移动的微型马达。初步数据表明，游泳压力及其对颗粒浓度的依赖性可以用来预测悬浮液的变化，包括相变，变形和运动，这是其他活性物质理论无法预测的。 该项目将通过进行一系列数值模拟来研究游泳压力及其在预测悬挂行为方面的效用。研究结果对制药、医药、食品等工业中活性物质悬浮液的加工有一定的指导意义。本文将从悬浮液中自推进粒子的游动压力出发，探讨悬浮液中自推进粒子自发自组装的微观机理。 基于加速斯托克斯动力学和其他方法的数值模拟将用于确定游泳压力随颗粒浓度、活动等的变化，其可用于制定悬浮液的非平衡状态方程和压力-体积相图。 粒子间的流体动力学相互作用将包括在计算中。 然后将游泳压力与活性颗粒的详细运动相关联，所述运动可以导致簇、聚集体和其他图案的自发形成，以及悬浮液的整体变形和运动。

CBET 1437570Suspensions containing particles that can propel themselves through a liquid are interesting examples of a class of materials called active matter. The self-propelled particles, which are sometimes thought of as swimmers, can contribute to the properties of the suspension as a whole. This project will explore a novel concept called the swim pressure that can help characterize the state of such a suspension. The swim pressure is similar to the usual pressure that molecules in a gas exert on the walls of a container, but in this case the pressure is exerted by self-propelled particles that could be microorganisms, chemically reactive particles, or micro-motors moving through liquid. Preliminary data suggest that the swim pressure and its dependence on particle concentration can be used to predict changes in the suspension, including phase changes, deformation and motion, that cannot be predicted by other theories for active matter. The project will investigate the swim pressure and its utility in predicting suspension behavior by carrying out a series of numerical simulations. The results will be useful to scientists and engineers who process active matter suspensions in pharmaceutical, medicinal, food and similar industries.The micromechanical origin of spontaneous self-assembly in suspensions of self-propelled particles will be investigated by focusing on the swim pressure exerted by the particles. Numerical simulations based on Accelerated Stokesian Dynamics and other methods will be used to determine the variation of swim pressure with particle concentration, activity, etc., which can be used to formulate a nonequilibrium equation of state and pressure-volume phase diagrams for the suspension. Hydrodynamic interactions among the particles will be included in the computations. The swim pressure will then be correlated with detailed motions of the active particles that can lead to spontaneous formation of clusters, aggregates and other patterns, as well as the overall deformation and motion of the suspension.