Departamento de Física, Facultad de Ciencias Físicas y Matemáticas, Universidad de Chile, Avenida Blanco Encalada 2008, Santiago, Chile.
Phys Rev E. 2019 Jan;99(1-1):012613. doi: 10.1103/PhysRevE.99.012613.
The rheology of semidilute bacterial suspensions is studied with the tools of kinetic theory, considering binary interactions, going beyond the ideal gas approximation. Two models for the interactions are considered, which encompass both the steric and short-range interactions. In these, swimmers can either align polarly regardless of the state previous to the collision, or they can align axially, ending up antiparallel if the relative angle between directors is large. In both cases, it is found that an ordered phase develops when increasing the density, where the shear stress oscillates with large amplitudes, when a constant shear rate is imposed. This oscillation disappears for large shear rates in a continuous or discontinuous transition, depending on if the aligning is polar or axial, respectively. For pusher swimmers these nonlinear effects can produce an increase on the shear stress, contrary to the prediction of a viscosity reduction made for the dilute regime with the ideal gas approximation.
用动理学理论的工具研究了半稀细菌悬浮液的流变学，考虑了二元相互作用，超越了理想气体近似。考虑了两种相互作用模型，它们都包含了空间和短程相互作用。在这些模型中，游动者要么在碰撞前的状态下无论极性都能对齐，要么它们可以轴向对齐，如果导向器之间的相对角度大，则最终会反向平行。在这两种情况下，当增加密度时，会发现当施加恒定剪切速率时，剪切应力会随着大振幅的振荡而发展出有序相。在连续或不连续转变中，对于大剪切速率，这种振荡会消失，具体取决于对齐是极性还是轴向。对于推式游动者，这些非线性效应可能会导致剪切应力增加，这与用理想气体近似对稀相进行的粘度降低预测相反。
