Drag reduction effects of dynamic superhydrophobic surface in turbulent channel*

Superhydrophobic surfaces (SHS) have been widely studied for the purposes of drag reduction by reducing skin friction drag. Experiments of patterned SHS with pressure control have successfully sustained wall-attached air films and have additionally shown that dynamic modulation of air film height can lead to even further drag reduction. Under such conditions, rapid change in the height and shape of the air film induce a jet-like flow structure with substantial wall-normal velocities (Wang and Gharib, J. Fluid Mech. 2020). We numerically simulate both the transient and fully developed behavior of these jets, using parameters matching those of the experiments. We investigate the effects of different dynamic air film height profiles on the characterization of the jet. Finally, the impact of this air film oscillation on drag reduction in a turbulent channel will be presented.