论文标题
成像细菌湍流的出现：相图和过渡动力学
Imaging the emergence of bacterial turbulence: phase diagram and transition kinetics
论文作者
论文摘要
我们通过实验研究集体细菌游泳的出现，这种现象通常称为细菌湍流。由细菌浓度，细菌的游泳速度和活性游泳者的数量跨越的3D大肠杆菌悬浮液流动的相图是系统的映射，这表明定量一致性与动力学理论一致，并证明了流体动力学相互作用在细菌集体游泳中的主要作用。更重要的是，我们突然增加了轻型细菌的游泳速度并实时向湍流形象，触发细菌湍流。我们的实验确定了两个异常的动力学途径，即，在相边界附近的长期孵化周期和由湍流相内深处驱动的两步转变的一步过渡。我们的研究不仅提供了现有理论的定量验证，还提供了对细菌湍流的颗粒间相互作用和过渡动力学的新见解。
We experimentally study the emergence of collective bacterial swimming, a phenomenon often referred to as bacterial turbulence. A phase diagram of the flow of 3D E. coli suspensions spanned by bacterial concentration, the swimming speed of bacteria and the number fraction of active swimmers is systematically mapped, which shows quantitative agreement with kinetic theories and demonstrates the dominant role of hydrodynamic interactions in bacterial collective swimming. More importantly, we trigger bacterial turbulence by suddenly increasing the swimming speed of light-powered bacteria and image the transition to the turbulence in real time. Our experiments identify two unusual kinetic pathways, i.e., the one-step transition with long incubation periods near the phase boundary and the two-step transition driven by long-wavelength instabilities deep inside the turbulent phase. Our study provides not only a quantitative verification of existing theories, but also new insights into interparticle interactions and transition kinetics of bacterial turbulence.
