Dynamical density functional theory for microswimmers.
Dynamical density functional theory for microswimmers.
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DOI：
10.1063/1.4939630
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发表时间：
2015-10
期刊：
影响因子：
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通讯作者：
A. Menzel;A. Saha;Christian Hoell;H. Löwen
中科院分区：
文献类型：
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作者：
A. Menzel;A. Saha;Christian Hoell;H. Löwen
动力学密度泛函理论(DDFT)已被成功地用于描述被动胶体悬浮液，包括单个颗粒之间的流体动力相互作用。另一方面，用DDFT表征了活跃的、“干”的自推进颗粒群体。在这里，我们更进一步，将这两种方法结合起来。我们建立了主动式微泳运动员悬吊的DDFT模型。为此，介绍了简单的微型模型微泳者。这些微泳者通过让周围的液体进入运动来自我推进。它们通过主动的自诱导流体流动和常见的“被动”流体动力相互作用来相互作用。有效的软空间斥力也被考虑在内。我们从常用的统计方法出发，推导出了DDFT。然后，我们的DDFT通过描述微泳者的悬浮体来测试和应用，该悬浮体的运动被限制在三维整体流体中的平面上。此外，游泳者受到径向对称的诱捕势的限制。在某些参数范围内，我们发现转动对称性的破缺与“流体动力泵浦状态”的形成相结合，这是以前通过基于粒子的模拟在文献中观察到的结果。揭示了这种泵浦状态的另一个不稳定性。
Dynamical density functional theory (DDFT) has been successfully derived and applied to describe on one hand passive colloidal suspensions, including hydrodynamic interactions between individual particles. On the other hand, active "dry" crowds of self-propelled particles have been characterized using DDFT. Here, we go one essential step further and combine these two approaches. We establish a DDFT for active microswimmer suspensions. For this purpose, simple minimal model microswimmers are introduced. These microswimmers self-propel by setting the surrounding fluid into motion. They hydrodynamically interact with each other through their actively self-induced fluid flows and via the common "passive" hydrodynamic interactions. An effective soft steric repulsion is also taken into account. We derive the DDFT starting from common statistical approaches. Our DDFT is then tested and applied by characterizing a suspension of microswimmers, the motion of which is restricted to a plane within a three-dimensional bulk fluid. Moreover, the swimmers are confined by a radially symmetric trapping potential. In certain parameter ranges, we find rotational symmetry breaking in combination with the formation of a "hydrodynamic pumping state," which has previously been observed in the literature as a result of particle-based simulations. An additional instability of this pumping state is revealed.