A combined rheometry and imaging study of viscosity reduction in bacterial suspensions
A combined rheometry and imaging study of viscosity reduction in bacterial suspensions
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DOI：
10.1073/pnas.1912690117
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发表时间：
2020-02-04
影响因子：
11.1
通讯作者：
Poon, Wilson C. K.
中科院分区：
文献类型：
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作者：
Martinez, Vincent A.;Clement, Eric;Poon, Wilson C. K.
在液体中悬挂自走式“推进器”可以降低液体的粘度。我们研究这种现象如何依赖于系统大小的细菌悬浮液使用体积流变仪和颗粒跟踪流变成像。在将黏度降至零所需的临界细菌体积分数（phi(c)近似于0.75%）以上，在静止状态下出现大规模集体运动，流动变得非线性。我们证实了一个理论预测，即这种不稳定性应该被约束抑制。我们的结果还表明，最近主动液晶理论在这种系统中的应用是站不住脚的。
Suspending self-propelled "pushers" in a liquid lowers its viscosity. We study how this phenomenon depends on system size in bacterial suspensions using bulk rheometry and particle-tracking rheoimaging. Above the critical bacterial volume fraction needed to decrease the viscosity to zero, phi(c) approximate to 0.75%, large-scale collective motion emerges in the quiescent state, and the flow becomes nonlinear. We confirm a theoretical prediction that such instability should be suppressed by confinement. Our results also show that a recent application of active liquid-crystal theory to such systems is untenable.