Design and Construction of Increasing- and Reducing-drag Surfaces Inspired by Asymmetrical Structure of Snakeskin

Elaphe snake is a widely distributed snake, mainly living in coastal lowlands, inland plains, hills and mountains and other areas, which is quick to react and can move quickly in a variety of environments. In order to explore the mystery of the fast movement of the brocade snake, we observed the belly and the notum of the snake, and found that the two parts have completely different structures. In this regard, the scales on the notum of the snake show a transverse ordered convex structure, which is conducive to the movement of drag reduction. The scales of the belly of the snake present a longitudinal and orderly convex structure, which is conducive to increase the friction between the snake and the contact surface, so as to facilitate its rapid forward movement. Inspired by this, we take different surface structures of snakeskin belly and notum as models, starting from two aspects of structural differences and functional differences of snakeskin belly and notum, and prepare biomimetic materials with drag-increasing and drag-reducing functions respectively through the method of complex shape. In addition, we built a simulation model based on the microstructure of the belly and notum of the snake. Through finite element simulation analysis, we revealed that the special surface microstructure of the snake can effectively realize the drag-increasing and drag- reducing functions of the material surface. This work lays a foundation for the application of functional interface materials.