Flow Characterization over Biomimetic Fish Scale Arrays
Abstract
The contributions of drag to energy consumption in the transportation sector are significant and often unavoidable. Biomimetic surfaces are promising as passive drag reduction mechanisms. Among them, fish scale arrays are beneficial in the laminar and transitional flow regimes but lack fundamental understanding. This research addressed this need and investigated the underlying flow mechanisms over fish scale arrays. Experimental measurements revealed the presence of flow recirculation, streamwise velocity streaks, spanwise velocity fluctuations, and wall normal vorticity streaks, all of which play a role in the near wall flow behaviour. Numerical simulations revealed the superior friction drag reduction capabilities of the diamond scale shape. The findings highlight how the surface variations contribute to the formation of flow behaviours which influence the skin friction and contribute to delaying the transition to turbulence. The improved understanding of underlying processes from this study will aid the optimization of scale shape to reduce drag.