OAC Core: Small: Efficient and scalable tools for design and analysis of active matter systems

“活性物质”一词指的是一类新的非平衡材料，由自驱动的成分组成，通过将环境中的能量(通常是化学能)转化为机械功(运动或游泳)来提供动力。它们在自然界中非常丰富，从有生命的到无生命的；这个术语可以用来描述自组织成具有化学活性的胶体颗粒的鸟群或细菌群。活性物质的共同特征是集体运动、反常涨落和无法用平衡物理学解释的力学性质。到目前为止，大多数研究都是在小系统或有限数量的粒子上进行的，目的是通过过度简化的属性描述符来理解潜在的行为。这个项目试图开发一个框架，使人们能够理解和利用活性物质系统的性质；为了推进这一工程飞跃，项目组打算开发一个公开可用的虚拟实验室--快速活性物质模拟器(FAMS)，它将能够通过高效的离散粒子方法对新的活性物质系统进行原型制作。为了实现广泛传播，该项目将创建当地的K-12扩展计划，利用REU为本科生提供的机会，招收代表性不足的学生，并将计算技术纳入我们的本科生和研究生课程。拟议的研究将改变活性物质研究的最先进水平，从理解简单的正则系统到设计能够对活性物质进行工程/操纵以建立系统的工具。要做到这一点，需要考虑颗粒的形态、周围环境、外力等。由于问题本质上是多尺度的，因此需要开发在这些尺度上有效的严格方法，并通过结合颗粒形状、障碍物的复杂几何形状和限制边界的细节来完全解决长距离和短距离的相互作用。为了实现上述目标，项目组将在四个不同的领域进行研究和开发：(A)通过等距方法在几何体上进行几何学和物理学的更高阶表示，以确保保真度而不需要高成本；(B)在基于边界积分式的框架内使用这些表示法；(C)与一套加速技术相结合，以减少内存和计算瓶颈，以便于分析真实的聚合；以及(D)与现有的库集成，以利用线性代数(密集和稀疏)的并行算法。该项目将使用这一框架来描述材料属性和集体动力学。这些新方法将改变活跃物质研究的最先进水平，从理解简单的正则系统到构建工具，使活跃物质的工程/操纵能够建立虚拟的“活”系统。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

The term "active matter" denotes a novel class of non-equilibrium materials made up of constituents that are self-driven, powered by converting the energy in the environment (typically chemical energy) to mechanical work (locomotion or swimming). They are abundant in nature, from the animate to the inanimate; this terminology can be used to describe flocks of birds or swarms of bacteria that self-organize to chemically active colloidal particles. The common characteristics of active matter are collective motion, anomalous fluctuations, and mechanical properties that cannot be explained by equilibrium physics. To date, most studies have been on small systems or a limited number of particles with the goal of understanding the underlying behavior with over-simplified property descriptors. This project seeks to develop a framework that will enable both understanding and exploiting the properties of active matter systems; to take this engineering leap forward, the project team intends to develop a publicly available virtual laboratory, the Fast Active Matter Simulator (FAMS), that will enable prototyping of novel active matter systems via efficient discrete particle methods. To enable widespread dissemination, the project will create local K-12 outreach programs, leverage REU opportunities for undergraduate students, recruit under-represented students, and incorporate computational techniques into our undergraduate and graduate curriculum. The proposed research will transform the state-of-the-art in active matter research, from understanding simple canonical systems to design tools that would enable engineering/manipulation of active matter to build systems. To do so, one needs to account for the morphology of particles, ambient environment, external forces, etc. As the problem is inherently multiscale, one needs to develop rigorous methods that are efficient across these scales, and fully resolve the long- and short-range interactions by incorporating the details of particle shapes, complex geometries of obstacles, and confinement boundaries. To realize the above objectives, the project team will perform research and development in four different areas; (a) higher-order representation of both geometry and physics on the geometry via isogeometric methods so as to guarantee fidelity without high cost, (b) casting these representations within a boundary integral equation based framework, (c) integrating with a set of acceleration techniques to reduce memory and computational bottlenecks to facilitate analysis of realistic aggregates, and (d) integration with existing libraries to leverage parallel algorithms for linear algebra (dense and sparse). The project will use this framework to characterize material properties and collective dynamics. These new methods will transform the state-of-the-art in active matter research, from understanding simple canonical systems to building tools that would enable engineering/manipulation of active matter to build virtual “living” systems.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.