The deformations of flagella are important in the motility of single- and multi-flagellated bacteria. Existing numerical methods have treated flagella as extensible filaments with a large extensional modulus, resulting in a stiff numerical problem and long simulation times. However, flagella are nearly inextensible, so to avoid large extensional stiffness, we introduce inextensible elastic rod models with hydrodynamics treated by a surface distribution of regularized Stokeslets. We benchmark this new model against previously described models of extensible elastic rods with hydrodynamics treated by a centerline distribution of regularized Stokeslets and rotlets, as well as a surface distribution of regularized Stokeslets. We compare the accuracy of the inextensible model with the extensible models and illustrate for which ratios of stretching/bending stiffness (which depend on the diameter of filament) the inextensible model is accurate and more efficient. We show that our inextensible approach can be markedly more efficient than the extensible models for many biological filaments. We also compare the accuracy of the centerline distribution of the Stokeslets and rotlets to the more accurate surface distribution of Stokeslets for modeling fluid-structure interactions of filaments.

鞭毛的变形在单鞭毛和多鞭毛细菌的运动中很重要。现有的数值方法已经将鞭毛视为具有大的拉伸模量的可伸长细丝，从而导致僵化的数值问题和较长的仿真时间。但是，鞭毛几乎不可伸展，因此，为避免较大的伸展刚度，我们引入不可伸展的弹性杆模型，该杆模型具有通过正则Stokeslets的表面分布处理的流体动力学。我们将该新模型与之前描述的可伸缩弹性棒模型进行了基准比较，该模型具有通过正则Stokeslets和rotlet的中心线分布以及正则Stokeslets的表面分布来处理的流体力学。我们将不可扩展模型的准确性与可扩展模型进行了比较，并说明了不可扩展模型对于哪些拉伸/弯曲刚度比（取决于细丝直径）是准确且更有效的。我们表明，对于许多生物细丝，我们的不可扩展方法比可扩展模型效率更高。我们还比较了Stokeslets和rotlets的中心线分布的精度与Stokeslets的更精确的表面分布的精度，以模拟细丝的流固耦合。