How hydrodynamics influences the collective motion of microswimmers: A particle-based simulation study

流体动力学如何影响微型游泳者的集体运动：基于粒子的模拟研究

基本信息

批准号：
254465319
负责人：
Professor Dr. Holger Stark
金额：
--
依托单位：
Institut für Theoretische Physik
依托单位国家：
德国
项目类别：
Priority Programmes
财政年份：
2014
资助国家：
德国
起止时间：
2013-12-31 至 2022-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/254465319?language=en
关键词：
How hydrodynamics influences collective motion

项目摘要

Microswimmers are systems in non-equilibrium and show a variety of intriguing collective motional patterns ranging from density waves and convection rolls to turbulence. The collective dynamics of microswimmers, active rods, and filaments is often modeled on the basis of coarse-grained continuum theories or with particle-based simulations, where hydrodynamic flow fields are neglected. In the second period of the priority program we will continue with our study, how hydrodynamics influences the collective motion of microswimmers. We will use the parallelized computer code, developed in the first period, where a collection of the model swimmers called squirmers is simulated in a fluid environment using the simulation technique of multi-particle collision dynamics (MPCD).We will continue our investigation of the collective dynamics of microswimmers under gravity concentrating on the formation of floating rafts, which are seen in active emulsions, and on the effect of an aligning torque (bottom-heavy swimmers). Here, intriguing collective patterns such as convection rolls and plumes are expected reminiscent of bioconvection of microorganisms. We then glue squirmers together to form active rods and flexible filaments. They will enable us to explore how the full hydrodynamics influences collective patterns such as bacterial turbulence or density waves and the intriguing dynamics of liquid-crystal defects in systems of dense active bio-polymers. Real microswimmers typically move in a viscoelastic environment. We will thus implement a viscoelastic fluid in MPCD and show how this changes the motion of single and a collection of squirmers.

微型游泳器是非平衡系统，表现出各种有趣的集体运动模式，从密度波、对流滚转到湍流。微型游泳器、主动杆和细丝的集体动力学通常基于粗粒连续理论或基于粒子的模拟进行建模，其中忽略了流体动力流场。在优先计划的第二阶段，我们将继续研究流体动力学如何影响微型游泳者的集体运动。我们将使用第一阶段开发的并行计算机代码，其中使用多粒子碰撞动力学（MPCD）模拟技术在流体环境中模拟一组称为蠕动者的模型游泳者。我们将继续研究重力作用下微型游泳者的集体动力学集中于浮筏的形成（在活性乳液中可见）以及对准扭矩（底部重的游泳者）的影响。在这里，对流辊和羽流等有趣的集体模式预计会让人想起微生物的生物对流。然后，我们将蠕动体粘合在一起，形成活性棒和柔性细丝。它们将使我们能够探索完整的流体动力学如何影响集体模式，例如细菌湍流或密度波，以及致密活性生物聚合物系统中液晶缺陷的有趣动力学。真正的微型游泳者通常在粘弹性环境中移动。因此，我们将在 MPCD 中实现粘弹性流体，并展示这如何改变单个蠕动体和一组蠕动体的运动。