Shark Inspired MAKO Surface for Steady Laminar Separation Control

Shortfin mako sharks have incredible agility and speed and it has been discovered that their flexible scales play an important role in this ability, despite being only about 200 𝜇m in size. In the presence of reversing flow, their scales can passively bristle up to angles of 50 degrees and this bristling capability has been shown to help control separation in water tunnel testing of real shark skin samples. This study investigated whether a mako shark inspired 3D printed flexible scale model (designated MAKO model) could act as a passive flow control device to control laminar separation. A previous experiment done with real shark skin in laminar flow showed separation control and this study attempted to reproduce those results with the MAKO model. Laminar boundary layer separation and subsequent reversing flow was induced with an adverse pressure gradient (APG) that was generated by a rotating cylinder above a flat plate in a boundary layer for four different Re up to 4x10⁵. DPIV was used to measure the flow for a baseline case over the smooth plate. The same method was also used over two different plates where the MAKO models, which had crown lengths of 2.4 mm and 3.6 mm, were embedded so the degree of flow separation could be compared between the cases.