Research on Composite Drag Reduction Characteristics of ‎Biomimetic Microstructural Surface

Abstract

The objective of this work is to investigate the effect of the bionic microstructure surface on flow field structure of the slab. The motivation behind this study is to investigate the effect of the bionic microstructure parameters including the height and intersection angle of microstructure in order to improve the drag reduction characters. The numerical simulation is performed on the bionic microstructure model of the V-shaped and serrated bionic microstructures using the RNG k-ε model. The drag reduction rates of two bionic microstructures under different dimensionless sizes are ob13.79 tained. The drag reduction efficiency is up to 8.76% when the dimensionless height of microstructure is at and the intersection angle for V-shaped microstructure. In addition, combined with wall temperature control of drag reduction technology, the influence of wall temperature on the drag reduction effect is also analyzed. Compared with the flow field structure of the surface boundary layer of the smooth plate, the wall microstructure divides the surface boundary layer into two parts: the bottom and the tip. The average velocity profile is moved up and the thickness of the linear bottom layer is increased. A large number of "quiet" fluids are gathered at the bottom of the surface boundary layer. In addition, the existence of wall microstructure can weaken the momentum exchange in the boundary layer and restrain the spreading vortex motion of the fluid in the near-wall region. The "secondary vortex pair" on both sides of the tip of the microstructures can effectively limit the lateral pulsation of fluid So as to achieve a good drag reduction effect‎.