Optimal slip velocities of micro-swimmers with arbitrary axisymmetric shapes
Optimal slip velocities of micro-swimmers with arbitrary axisymmetric shapes
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DOI：
10.1017/jfm.2020.969
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发表时间：
2021-01-13
影响因子：
3.7
通讯作者：
Veerapaneni, Shravan
中科院分区：
文献类型：
--
作者：
Guo, Hanliang;Zhu, Hai;Veerapaneni, Shravan
本文提出了一种确定悬浮在粘性流体中的轴对称微泳者在任意给定形状下的最佳滑移速度的计算方法。其目标是最大限度地减少功率损失，以保持目标游泳速度，或等效地最大化微泳者的效率。由于控制流体运动的Stokes方程是线性的，我们证明了这个偏微分方程组约束优化问题归结为一个更简单的二次优化问题，其解可以用高精度边界积分方法来求解。我们考虑了用约化体积参数表示的各种形状，并计算了它们的游动效率。其中，长椭球体被发现是在给定的缩小体积下最有效的微泳者形状。我们提出了一种简单的基于形状的标量度量，它可以确定给定形状上的最佳滑移是否使其成为推手、拉手或中立游泳运动员。
This article presents a computational approach for determining the optimal slip velocities on any given shape of an axisymmetric micro-swimmer suspended in a viscous fluid. The objective is to minimize the power loss to maintain a target swimming speed, or equivalently to maximize the efficiency of the micro-swimmer. Owing to the linearity of the Stokes equations governing the fluid motion, we show that this PDE-constrained optimization problem reduces to a simpler quadratic optimization problem, whose solution is found using a high-order accurate boundary integral method. We consider various families of shapes parameterized by the reduced volume and compute their swimming efficiency. Among those, prolate spheroids were found to be the most efficient micro-swimmer shapes for a given reduced volume. We propose a simple shape-based scalar metric that can determine whether the optimal slip on a given shape makes it a pusher, a puller or a neutral swimmer.