Viscosity of bacterial suspensions: Hydrodynamic interactions and self-induced noise
Viscosity of bacterial suspensions: Hydrodynamic interactions and self-induced noise
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DOI：
10.1103/physreve.83.050904
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发表时间：
2011-05-16
影响因子：
2.4
通讯作者：
Aranson, Igor S.
中科院分区：
文献类型：
--
作者：
Ryan, Shawn D.;Haines, Brian M.;Aranson, Igor S.
对游动细菌悬浮液的粘度进行了解析和数值研究。我们提出了一个简单的模型，允许大量的细菌进行有效的计算。我们的计算表明，长程流体动力学相互作用，固有的自粘性流体中的物体，导致在一个显着减少的有效粘度。与枯草芽孢杆菌悬浮液的实验一致，我们表明，粘度降低与由于游泳者之间的相互作用而引起的大规模集体运动的发生有关。模拟结果表明，粘度降低只发生在相对较低浓度的游泳者：浓度的进一步增加会导致粘度的增加。我们推导出一个明确的渐近公式的有效粘度在已知的物理参数，并表明，流体动力学相互作用表现为自诱导噪声在系统中没有任何明确的随机性。
The viscosity of a suspension of swimming bacteria is investigated analytically and numerically. We propose a simple model that allows for efficient computation for a large number of bacteria. Our calculations show that long-range hydrodynamic interactions, intrinsic to self-locomoting objects in a viscous fluid, result in a dramatic reduction of the effective viscosity. In agreement with experiments on suspensions of Bacillus subtilis, we show that the viscosity reduction is related to the onset of large-scale collective motion due to interactions between the swimmers. The simulations reveal that the viscosity reduction occurs only for relatively low concentrations of swimmers: Further increases of the concentration yield an increase of the viscosity. We derive an explicit asymptotic formula for the effective viscosity in terms of known physical parameters and show that hydrodynamic interactions are manifested as self-induced noise in the absence of any explicit stochasticity in the system.