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：已知鞭毛的束集能产生“游动”阶段，此时细菌沿近似直线运动而非改变方向。历史上，束集现象的力学解释引发了许多研究者的兴趣，并在物理模型和实验方法上取得了重大进展。本研究提出了一种细菌启发的厘米级软体机器人硬件平台，以及用于多鞭毛机器人在低雷诺数（约0.1）物理仿真模型的计算框架。流固耦合模拟将离散弹性杆算法与正则化斯托克斯流段方法相结合，通过基于罚函数的方法处理两根鞭毛之间的接触。通过实验与仿真结果的比较，验证了该仿真工具能捕捉问题的本质物理过程。初步研究发现，束集现象提供的抗屈曲鲁棒性以及多鞭毛软体机器人的效率均优于单鞭毛对照机器人。同时观察到几何与弹性之间的耦合效应，表现为机器人推进速度对鞭毛转速的非线性依赖关系。