基于PIV的拉萨裸裂尻摆尾压力场特征分析

为研究鱼体摆尾时压力场分布特征及其游泳动力的形成过程,本文以拉萨裸裂尻幼鱼为研究对象,利用粒子图像测速技术(PIV)获得幼鱼在自由游泳摆尾的压力分布规律。结果表明:幼鱼需要借助尾鳍的摆动来形成射流推动鱼体前进,沿着尾部轮廓的凹陷处流体压力为负值,正压则沿着尾部轮廓的凸起处分布;拉萨裸裂尻幼鱼的整个摆尾过程可分为"S"形(T=0～50ms)、"C"形(T=50～150ms)和"C"形回摆(T=150～400ms)三个阶段。"S"形阶段,正压区合力F随时间T先减小后增大,负压区合力F随时间T先增大后减小,正压区和负压区的合力F分布范围为0.88～1.03mN/BL、-0.86～-0.38mN/BL;"C"形阶段,正压区和负压区的合力F分别逐渐增大至3.45mN/BL、-1.62mN/BL;"C"形回摆阶段,正压区和负压区的合力F分别逐渐减小至-0.43mN/BL、1.63mN/BL。

Analysis on the pressure field characteristics of schizopygopsis younghusbandi Regan tail swinging based on PIV

In order to study the characteristics of pressure field distribution during the tail swinging of fish body and the formation process of swimming dynamic force,the pressure distribution rules for free swimming juvenile fish of schizopygopsis younghusbandi Regan when swinging tail are obtained by Particle Image Velocimetry(PIV)technology.The results show that the juvenile fish needs to form a jet by swinging its caudal fin to move forward.The negative pressure is distributed along the depression of the tail profile,and the positive pressure is distributed along the bulge of the tail profile.The whole process of tail swinging can be divided into three stages,including "S"type(T=0~50 ms),"C"type(T=50~150 ms)and"C"type with back swinging(T=150~400 ms).In the"S"-type stage,the resultant force Fof the positive pressure zone decreases firstly and then increases with time,and it is just the opposite in the negative pressure zone.The distribution of resultant force Fin the positive and negative pressure zones ranges from 0.88 to 1.03 mN/BL and from-0.86 to-0.38 mN/BL,respectively.In the"C"-type stage,the resultant force Fof the positive pressure zone and the negative pressure zone will gradually increase to 3.45 mN/BL and-1.62 mN/BL,respectively.In the stage of"C"-type with back swinging,the resultant force Fof the positive pressure zone and the negative pressure zone will gradually reduce to-0.43 mN/BL,1.63 mN/BL,respectively.