CFD Analysis of Flow near Shark Skin Model with Vibration for Improvement of Antifouling Properties of Ship Bottom: Analysis of Flow near Multiple Denticles that Compose Shark Skin

researches related to bio-inspired shark skin’s drag reduction and antifouling to improve fuel consumption of ships. But the bio-inspired shark skin has a demerit that antifouling effect of skins is lost when they are at anchor in a few weeks. In this study, to add the antifouling effect on the bio-inspired shark skins at anchor, the vibration of the skin is tried to be used. As for the targeted model, real shark skin model is created by using µCT figures of mako shark skin. Flow field around the shark skin is analyzed by CFD when real shark skin or flat skin vibrate. The fluid is water and it is treated as laminar flow. To simulate flow field by sinusoidal vibration of shark skin, opposite side to skin is treated as inlet and shark skin side except for shark skin is treated as outlet. As for the boundary condition for these parts, velocity and pressure are given as sinusoidal wave at the inlet, and pressure is 0 at the outlet. And boundary condition at shark skin and other sides are treated as fixed wall. In addition, wall shear stress on one denticle and two denticles is analyzed. As a result, it is shown that flow field near shark skin is complicated and maximum wall shear stress on the skin increases as frequency of vibration increases. And there is linear relationship between flow velocity and wall shear stress. In the case of vibration of two denticles of shark skin, wall shear stress on the skin is influenced by distance and angle between two denticles. It is concluded that (1) The possibility of adding antifouling effect on shark skin increases with vibration, (2) Wall shear stress on shark skin will be increased by optimizing distance and angle between two denticles in the case of vibration.