We introduce a numerical framework to study the fluid-structure interaction between two helical filaments rotating under low Reynolds number condition, motivated by the propulsion of bacteria using helical flagella. Our numerical framework couples the elasticity of the thin filaments, nonlocal hydrodynamic loading, and the contact between multiple elastic rods. Each of these three ingredients is respectively modeled by the Discrete Elastic Rods method (for a geometrically nonlinear description of soft filaments), Regularized Stokeslet Segments method (for the nonlocal drag force in a viscous fluid), and non-penetration condition between rod segments. Two helical rods rotating side by side attract each other and become closer because of their hydrodynamic interplay in a viscous environment. Depending on the initial distance between the two and their rotational frequency, the two filaments can come in physical contact. Exploiting the efficiency and robustness of the simulator, we perform a systematic parameter sweep to quantify the bundling behavior. The findings may shed light on the physics of the bio-locomotion of microorganisms and inspire the design of novel biomimetic soft robots.

我们引入了一个数值框架来研究在低雷诺数条件下旋转的两个螺旋丝之间的流固耦合，这是由使用螺旋鞭毛的细菌推动的。我们的数值框架将细丝的弹性、非局部流体动力载荷和多个弹性杆之间的接触耦合起来。这三种成分中的每一种都分别通过离散弹性杆方法（用于软丝的几何非线性描述）、正则化斯托克斯雷线段方法（用于粘性流体中的非局部阻力）和杆段之间的非穿透条件建模。并排旋转的两个螺旋杆相互吸引并由于它们在粘性环境中的流体动力相互作用而变得更近。根据两者之间的初始距离及其旋转频率，两条细丝可以进行物理接触。利用模拟器的效率和稳健性，我们执行系统参数扫描以量化捆绑行为。这些发现可能有助于阐明微生物生物运动的物理学，并启发新型仿生软机器人的设计。