SGER: Motility, Mixing, and Multicellularity

本次SGER奖合作的总体研究目标是剖析运动性与全球运输和混合的耦合的物理问题。传统上，输运被认为是由分子溶质的扩散主导的，平流起次要作用。然而，活动微生物鞭毛的集体动态可以产生空间上延伸的、通常是混乱的流动。这些流动以大的Peclet数为特征，伸展和折叠；它们可能从根本上增加运输，从传统上认为控制这些生物系统的东西。利用两个互补的复杂生物系统，自我浓缩的细菌和集群的草藻，该小组将量化平流和混合，以及流动动力学的空间和时间相关性，使用粒子成像测速(PIV)来跟踪示踪剂颗粒和生物体。同时研究这种表面上不相容的系统，应该会揭示出适用于更普遍的流体动力学共性。该实验计划将检验最近关于这些现象的理论分析，并指导这些集体流动的适当多体理论的发展。从事该项目的学生将受益于这一新的和快速增长的生物微流变学科学领域的跨学科。

The overall research goal of the collaboration in this SGER award is to dissect the physical problem of the coupling of motility with global transport and mixing. Conventionally, transport is viewed as dominated by the diffusion of molecular solutes, with advection playing a minor role. Yet, the collective dynamics of the flagella of motile microorganisms can generate spatially extended, often chaotic flows. These flows feature large Peclet numbers, stretching and folding; they may radically augment transport from that which is conventionally thought to govern these biological systems. Using two complementary complex biosystems, self-concentrated bacteria and colonial volvocalean algae, the group will quantify advection and mixing, together with spatial and temporal correlations of the flow dynamics, using particle imaging velocimetry (PIV) to track tracer particles and organisms. Investigating concurrently such superficially incommensurate systems should reveal fluid dynamical commonalities that apply far more generally. The experimental program will test recent theoretical analyses concerning these phenomena and guide in the development of appropriate many-body theories of these collective flows. Students working on the project will benefit by the interdisciplinarity within this new and rapidly-growing bio-microfluidics area of science.