3D-printed Models Inspired by Sinusoidal Dolphin Skin Geometry to Control Flow Separation

The dolphin is among the fastest marine animals, and therefore has attracted the research interest of both biologists and engineers. A unique feature of dolphin skin is the rows of transverse grooves that resemble a wave-like geometry circumferentially covering a large portion of their body. It is hypothesized that the subtle sinusoidal grooves create a partial slip condition over embedded vortices within cavities while inducing mixing that increases the flow momentum in the boundary near the surface thereby acting as a passive mechanism to delay flow separation to reduce pressure drag while swimming. Previous research showed that sinusoidal grooves, compared to rectangular, have a less intrusive streamlined shape to achieve the desired. This study investigates the effect of geometric amplitude for 3D printed sinusoidal grooved models dimensionally matched to the wavelength observed on dolphin skin.  DPIV experiments measured boundary layer profiles for the various surface geometries as well as a smooth plate within a separating turbulent boundary layer to determine the degree of separation control capability for each case.