Bundled slender-body theory for elongated geometries in swimming bacteria
Bundled slender-body theory for elongated geometries in swimming bacteria
复制标题
DOI：
10.1103/physrevfluids.5.053102
复制
发表时间：
2020-05
期刊：
影响因子：
--
通讯作者：
B. Liu;Jeremias Gonzalez
中科院分区：
文献类型：
--
作者：
B. Liu;Jeremias Gonzalez
活微生物的大小和形状已被认为是其在粘性流体中运动的重要因素。要了解细胞几何形状的细微变化如何影响水动力，需要求解三维 (3D) 斯托克斯方程，例如通过边界积分法求解物体的 2D 表面。减少这些计算成本涉及使用可用的对称性来简化边界几何形状，例如通过身体中心线表示细长体，称为细长体理论。在这里，我们扩展了标准细长体理论可以处理的纵横比范围，通过用一束细丝表示身体，每个细丝仍然大致满足细长体标准。我们证明，这种捆绑细长体理论可用于确定水动力对运动物体不同几何因素的依赖性。作为该方法的直接应用，我们研究了具有弯曲细胞体并通过旋转螺旋鞭毛游泳的单毛细菌的优化运动学。我们表明，其细胞体的曲率可以在游泳运动中发挥重要作用，这取决于细胞鞭毛排列中出现的手性。
Size and shape of a living microorganism have been recognized as important factors for its movement through a viscous fluid. Understanding how subtle variations in cellular geometry affect the hydrodynamic forces requires solving three-dimensional (3D) Stokes equations, e.g., by resolving an object’s 2D surface in a boundary integral method. A reduction of these computational costs involves using available symmetries to simplify the boundary geometries, such as representing a slender body by its body centerline, known as the slender-body theory. Here, we extend the range of the aspect ratio that can be treated by a standard slender-body theory, by representing the body with a bundle of thin filaments that each still approximately satisfies the slender-body criteria. We show that this bundled slender-body theory can be used to determine the dependency of hydrodynamic forces on varying geometric factors of a moving object. As a direct application of this method, we study the optimized kinematics of a monotrichous bacterium that has a curved cell body and swims by rotating a helical flagellum. We show that the curvature in its cell body can play a nontrivial role in the swimming motility, depending on the chirality emerging from the cell-flagellum alignment.