中文摘要：

以“尼罗河魔鬼”鱼的柔性长背鳍扭波推进模式为研究对象，通过观察活鱼的游动模式，提取影响扭波推进的运动学要素，建立了描述柔性长背鳍扭波推进时动态曲面的数学模型。研究了鳍条仰角与摆动规律对鳍面的影响。最后，用细长体理论分析并计算出推力分布。研究表明，鳍条仰角在φ=85°的情况下所形成的鳍面与垂直鳍条所形成的鳍面相比，其最大偏离值与鳍长之比为1．79，可以用垂直于基线的鳍条制作模型；鳍条按正弦规律摆动时所形成的扭波波形鳍面与实鱼鳍面相似。

英文摘要：

A mathematic mode was established to describe the torsional wave propulsion by the long flexible fin of Gymnarchus niloticus. The kinematics essential factors which affect the torsional wave propulsion were obtained after the observation of the swimming mode of live fish. The effect of fin ray＇s elevationg and oscillating pattern on the fin＇s surface were studied. Finally, the elongated body theory was used to analyse and calculate the thrust distribution. The results show that the maximal ratio for offset to the ray＇s length is only 1.7% in the case of the fin ray＇s elevation 85°, so the vertical fin ray can be used to establish the fin model, and the torsional wave surface abiding by sine ruler is alike to the live fish＇s fin surface.