Propulsion and Interaction of Hot Brownian Swimmers

自热泳（热）微游泳是一种多用途的、典型的活性颗粒，由颗粒表面和附近底物加热激发的热渗透流驱动。它们有趣的非平衡布朗涨落在理论上和实验上都得到了很好的控制。我们高度优化的支持非平衡分子动力学模拟的并行数值代码建立了一个连接实验和理论的独立平台。基于前一个资助期的结果，我们将协调实验、模拟和理论，以进一步阐明游泳者之间的相互作用以及与基质表面的相互作用。我们将继续采用光子推动的创新技术来实现无力和无扭矩的热游泳者操纵和转向，并将其扩展到允许对热游泳者群的游泳压力和表面张力的实验控制测量。从理论上讲，我们将扩展我们最近在所谓的活性布朗粒子（ABP）相互作用组合的系统粗粒化方面的进展，我们可以明确地推导出所谓的游动压力和表面张力的形式表达式。我们将把这一分析扩展到具有动量守恒的（湿）微观模型，通过速度而不是经典的（干）ABP游泳力来表示游泳。最终，我们的目标是包含游泳者特定的相互作用揭示了我们的模拟和实验。在一个更实用的方向上，通过专门定制的人工交互来扩展或取代我们的热游泳者之间的物理交互将是有趣的。我们计划通过光子轻推实现反馈控制，作为游泳者通过交换（延迟）信息相互交互的机制。这些将适用于模拟生命系统中信息触发的群集效应。从长远来看，这将使我们的热游泳模型系统成为一个多功能的实验实验室，以模拟一般的活性物质系统。

Self-thermophoretic (hot) microswimmers are versatile and prototypical active particles driven by thermo-osmotic flows excited by heating at the particle surface and nearby substrates. Their interesting nonequilibrium Brownian fluctuations are theoretically and experimentally well under control. Our highly optimised parallel numerical code for supporting nonequilibrium molecular dynamics simulations establishes an independent platform to link experiment and theory. Based on the results of the preceding funding period, we will concert experiments, simulations, and theory to further elucidate the mutual interactions of swimmers and interactions with substrate surfaces. We will continue to employ the innovative technique of photon nudging for a force-free and torque-free manipulation and steering of hot swimmers, and extend it to allow for controlled measurements of the swim pressure and surface tension of flocks of hot swimmers experimentally. Theoretically, we will extend our recent progress in the systematic coarse-graining of interacting assemblies of so-called active-Brownian-particles (ABP), for which we could unambiguously derive formal expressions for the so-called swim pressure and the surface tension. We will extend this analysis to a (wet) microscopic model with momentum conservation, representing swimming by a velocity rather than by the classical (dry) ABP swim force. Eventually, we aim at an inclusion of the swimmer-specific interactions revealed by our simulations and experiments. In a more applied direction, it will be interesting to extend or supersede the physical interactions between our hot swimmers by specifically tailored artificial interactions. We plan to implement a feedback control via photon nudging as a mechanism for swimmers to mutually interact via an exchange of (delayed) information. These will be suitable to mimic the effect of information-triggered flocking in living systems. In the long run, this should turn our model system of hot swimmers into a versatile experimental laboratory to emulate generic active matter systems.