ABSTRACT
Objective To investigate mechanical characteristics of the spirochete flagella with tight-fitting ribbon configuration in micro-periplasmic space. Methods The 2D model of two parallel plates was used to simplify the periplasmic space, and the effects of flagellum spacing and eccentricity on force and torque acted on the spirochete flagella, and wall shear stress acted on the spirochete protoplasmic cylinder were studied by using numerical simulation method. Results (1) The relationship between the flagellum horizontal force and eccentricity was presented as a parabolic curve, and the peak value of the flagellum horizontal force was mainly caused by the gradual increase of pressure difference at two sides of the cylinder and the resistance viscous force as well. Flagellum spacing had no significant influence on flagellum horizontal force. (2) The relationship between the flagellum torque and eccentricity was presented as an exponential curve, and smaller flagella spacing would cause bigger flagella torque. (3) Flagellum spacing had no significant effect on wall shear stress of the protoplasmic cylinder, but it would be increased with the number of flagella and the eccentricity increasing. Conclusions Numerical simulation results in this study can qualitatively reflect mechanical characteristics of the spirochete flagella, and also provide references for further understanding the morphology of spirochete as well as its kinematic mechanism and pathogenic characteristics.