境界要素法によるべん毛の抵抗力理論の検討

抄録

The resistive force theory (RFT) is a conventional method for analyzing the motion of a microorganism swimming with a flagellum. This theory has been used in many analyses ; however, it has some flaws such as that hydrodynamic interaction between the cell body and the flagellum is ignored and the interaction between a portion of the flagellum and the remains is also ignored. In order to estimate these effects, the boundary element method (BEM) is applied to investigate the Stokes flow around a microorganism swimming with a rotating helical flagellum. First, force and torque of prolate spheroids and of circular cylinders are calculated to check the accuracy of the BEM. Fairly good agreement is obtained between the present results and the theoretical ones. Then, the mean propulsive velocity of a microorganism is calculated. The velocity agrees with that obtained by using the slender body theory (SBT) . The interaction between the cell body and the flagellum is small ; therefore, the RFT can be used to evaluate the force and the torque exerted on the flagellum. On the other hand, the interaction among the portions of the flagellum is quite large, and this causes differences in results between the BEM and the RFT. The results of the RFT are improved by adjusting resistance coefficients to include this interaction effect.