Experimental study on the drag reduction effect of a rotating superhydrophobic surface in micro gap flow field

In this paper, the drag reduction effect of a rotating disk with a superhydrophobic surface in micro gap flow field has been experimentally researched. The velocity distributions, driven by disks with a smooth and superhydrophobic surface, were measured using a rotating flow measurement system, based on micro particle image velocimetry in similar experimental conditions. The friction torques of different Reynolds numbers were calculated by integrating the shear stress in the radial direction to verify the drag reduction effect. The results showed a laminar regime with a merged boundary layer appearing in the axial gap and the tangential velocity was approximately linear along the z-axis at different radiuses. The maximum drag reduction rate reached 13.9 % for the existence of an air gap in the micro–nano structures of the superhydrophobic surface. This result provides a solution for solving the problem of solid–liquid friction when a solid object moves underwater in a micro system.