Author(s): Fakai Lei, Mengzhen Xu, Ziqing Ji, Zhaoyin Wang, Michael Andrew Bisset
Linked Author(s): Fakai Lei
Keywords: Blind fish, lateral line, CFD (computational fluid dynamics), 3D scan, pressure gradient.
Abstract: Sinocyclocheilus Tilei. hornes (Tilei. ) is one of the species of Chinese blind cave fishes, which has specific structures, e. g. head-horn. During thousands or millions of years living in caves, the species has developed a number of unusual adaptions, such as typical pigmentation and eyes degeneration into needle-like size or useless, developing a horn of two tile-like bulges. However, the function of the horn is not yet understood. The aim of this study is to reveal whether or how the horn function in helping the blind cavefish move and prey. Scientific hypothesis is proposed that the horn helps strengthen the interaction between the cave fish and the water flow, and make it easier to sense the signal from water flow. In this study, we attempt to understand the hydrodynamic image characteristics produced by the head horn of Tilei. by comparison of the pressure, flow field, resistance and lift force of Tilei. and Sinocyclocheilus Angus. tiporus (Angus. , a species that has similar size and body shape as Tilei. , but without horn) under the same hydrodynamic conditions. Numerical simulations were conducted using CFD (computational fluid dynamics) software. Simulation results show that there was a flow stagnation and high-pressure zone under the horn of Tilei. , resulting in the pressure gradient of Tilei. as high as twice of that of Angus. . In addition, Tilei. received significantly higher drag force and lift force than Angus. under the same flow condition. Such phenomenon was more remarkable under higher simulated flow velocity, which suggests that Tilei. might be slow swimmers. Furthermore, it was indicated that the interaction between the cave fish and the water flow was much more intensive for Tilei. than for Angus. , given the projection speed of the water flow as a standard. Therefore, we believe that the head-horn structure of cavefish may help strengthen their sense efficiency in water flow
Year: 2017