An effective and efficient model of the near-field hydrodynamic interactions for active suspensions of bacteria.
An effective and efficient model of the near-field hydrodynamic interactions for active suspensions of bacteria.
复制标题
细菌活性悬浮液近场流体动力相互作用的有效模型
DOI：
10.1073/pnas.2100145118
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发表时间：
2021-07-13
影响因子：
11.1
通讯作者：
Xu X
中科院分区：
文献类型：
--
作者：
Zhang B;Leishangthem P;Ding Y;Xu X
微泳者的主动悬挂表现出新的紧急行为(自组织、主动湍流等)。在宏观长度尺度上。对于这样的系统，至少有数千名微泳者，直接的水动力相互作用的数值模拟在计算上是不可行的，需要简化的模型。我们证明，现有的模型不能令人满意地描述近距离微泳者的水动力相互作用，甚至有定性错误的预测，这表明迫切需要一个合适的模型。我们提出了一个物理上有效且计算上有效的模型来描述这种流体动力学。我们模型的主要创新之处是通过阻力张量来描述流体动力相互作用，而不是现有模型中的有效空间相互作用。活动流体中的近场流体动力相互作用是决定所观察到的许多重要紧急行为的关键，但到目前为止还没有被成功地模拟。在这项工作中，我们提出了一个有效的模型，通过张量阻力系数来捕捉近场流体动力相互作用的本质，并通过由大肠杆菌和被动球体组成的教学模型系统进行了数值验证。在一个研究细菌-球体对动力学散射角的关键测试案例中，我们证明了近场流体动力学即使对于这个简单的两体系统也可以产生定性的差异：基于所提出的模型的计算揭示了参数空间中细菌被被动球体捕获的区域，这一现象在实验中经常被观察到，但不能用任何现有的模型来解释。最后，我们证明，我们的模型还可以有效地模拟含有数万个细菌的活动流体，这些细菌足以研究许多紧急行为。
Active suspensions of microswimmers demonstrate novel emergent behaviors (self-organizations, active turbulence, etc.) on macroscopic length scales. For such systems with, minimally, thousands of microswimmers, direct numerical simulations of the hydrodynamic interactions are computationally infeasible, and reduced models are needed. We demonstrated that existing models are not satisfactory in describing the hydrodynamic interactions for microswimmers in close proximity with even qualitatively erroneous predictions, indicating a pressing need for an adequate model. We propose a model that is both physically effective and computationally efficient in describing such hydrodynamics. The main novelty of our model is the description of hydrodynamic interactions through a resistance tensor, as opposed to an effective steric interaction in existing models. Near-field hydrodynamic interactions in active fluids are essential to determine many important emergent behaviors observed, but have not been successfully modeled so far. In this work, we propose an effective model capturing the essence of the near-field hydrodynamic interactions through a tensorial coefficient of resistance, validated numerically by a pedagogic model system consisting of an Escherichia coli bacterium and a passive sphere. In a critical test case that studies the scattering angle of the bacterium–sphere pair dynamics, we prove that the near-field hydrodynamics can make a qualitative difference even for this simple two-body system: Calculations based on the proposed model reveal a region in parameter space where the bacterium is trapped by the passive sphere, a phenomenon that is regularly observed in experiments but cannot be explained by any existing model. In the end, we demonstrate that our model also leads to efficient simulation of active fluids with tens of thousands of bacteria, sufficiently large for investigations of many emergent behaviors.
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DOI：
10.1073/pnas.1718294115
发表时间：
2018-03-27
影响因子：
11.1
作者：
Ohmura T;Nishigami Y;Taniguchi A;Nonaka S;Manabe J;Ishikawa T;Ichikawa M
通讯作者：
Ichikawa M
影响因子：
8.6
作者：
Li Y;Zhai H;Sanchez S;Kearns DB;Wu Y
通讯作者：
Wu Y
影响因子：
3.7
作者：
Ishimoto, Kenta;Gaffney, Eamonn A.
通讯作者：
Gaffney, Eamonn A.
影响因子：
3.4
作者：
Molina, John J.;Nakayama, Yasuya;Yamamoto, Ryoichi
通讯作者：
Yamamoto, Ryoichi
影响因子：
3.7
作者：
Ishikawa, Takuji;Simmonds, M. P.;Pedley, T. J.
通讯作者：
Pedley, T. J.