Presenter: Derrick Wiberg
Authors: Derrick Wiberg, Som Dutta
Faculty Advisor: Som Dutta
Institution: Utah State University
The purpose of this research is to examine the effect of shark denticles on drag reduction. These denticles are 0.2 - 0.5 mm in length and are attached to the epidermis by slender stems that allow them to bend and flex. Studies agree on their drag-reducing capabilities, experimentally determining 3-12% reduction values. Much of the drag-reduction research in recent years has examined static denticles attached to flat surfaces. However, in order to fully harness the drag-reducing capabilities of shark denticles, the simulated structures tested must evolve to include the denticles’ flexible characteristics. Shark denticles are embedded in naturally elastic epidermis, which allows them to naturally bristle up to an angle of 60°. The variation of the bristling angle potentially serves to reduce pressure drag and enable the denticles to act as vortex generators. As the denticle protrudes into the boundary layer, it produces turbulent mixing and results in prevention of flow separation. This effect could be enhanced by increasing the bristling angle of the denticle, causing the tail of the denticle protrude more into the boundary layer. The proposed research will examine denticles attached to a flat surface whose bristling angle will be adjusted dynamically based on flow conditions. This will be modeled using Nek5000, a high-order Spectral Element Method (SEM) based incompressible Navier-Stokes solver. These large-scale simulations will be conducted using resources from Center for High Performance Computing (CHPC) at the University of Utah and other petascale HPC platforms like Blue Waters (NCSA). Study of the active bristling effect of denticles on flat surfaces will uncover the complex interplay between the denticle dynamics and the vortex-shedding process. From this research, further study of the bristling effect on more complex surfaces will be made possible. Ultimately, this will facilitate research on optimizing lift-to-drag ratios of airfoils helping to improve energy efficiency.