Influence of morphology for drag reduction effect of sharkskin surface

Through millions of years' natural selection, creature has formed their own unique functional surfaces. Shark is one of the fastest animals in the ocean, which is well known for sharkskin effect. Sharkskin surface is all covered by tiny and rigid scales with sophisticated morphology, which is one important factor to produce the high drag reducing efficiency. However, the drag reduction mechanism of sharkskin has not been understood thoroughly, which has developed into an urgent problem to be resolved. In this paper, the accurate 3D digital model of sharkskin surface is constructed based on the biological prototype and the micro flow field on the near wall is analyzed comprehensively and deeply. In addition, the drag reduction mechanism is explored from different aspects, especially which, the influences of the variation of attack angles of scales, the super-hydrophobic effect and nanochain of mucus on drag-reducing efficiency are taken into consideration, which has great significance on academic research and engineering application.