The bundling of flagella is known to create a "run" phase, where the bacteria moves in a nearly straight line rather than making changes in direction. Historically, mechanical explanations for the bundling phenomenon intrigued many researchers, and significant advances were made in physical models and experimental methods. Contributing to the field of research, we present a bacteria-inspired centimeter-scale soft robotic hardware platform and a computational framework for a physically plausible simulation model of the multi-flagellated robot under low Reynolds number (~0.1). The fluid-structure interaction simulation couples the Discrete Elastic Rods algorithm with the method of Regularized Stokeslet Segments. Contact between two flagella is handled by a penalty-based method. We present a comparison between our experimental and simulation results and verify that the simulation tool can capture the essential physics of this problem. Preliminary findings on robustness to buckling provided by the bundling phenomenon and the efficiency of a multi-flagellated soft robot are compared with the single-flagellated counterparts. Observations were made on the coupling between geometry and elasticity, which manifests itself in the propulsion of the robot by nonlinear dependency on the rotational speed of the flagella.

翻译：已知鞭毛的捆束会产生“奔跑”阶段，此时细菌近乎直线运动而非改变方向。历史上，捆束现象的力学解释激发了众多研究者的兴趣，并在物理模型与实验方法上取得了显著进展。本文提出了一种受细菌启发的厘米级软体机器人硬件平台，以及一个针对低雷诺数（~0.1）下游动多鞭毛机器人的物理逼真仿真计算框架。该流固耦合仿真将离散弹性杆算法与正则化斯托克斯段方法相结合，通过罚函数法处理两根鞭毛间的接触。我们对比了实验结果与仿真结果，验证了该仿真工具能够捕捉该问题的核心物理过程。初步研究发现：捆束现象带来的抗屈曲鲁棒性，以及多鞭毛软体机器人的效率优于单鞭毛机器人。还观测到几何结构与弹性的耦合效应，表现为机器人推进速度与鞭毛转速呈非线性依赖关系。