RII Track-4: NSF: Simulation and Modeling of Turbulent Flow Control via Flow-Dependent Anisotropic Surface Textures

University Of Mississippi, University MS

Investigators

Abstract

Flow separation is the phenomenon that occurs when a fluid particle is slowed down and cannot follow the shape of the surface. It has several negative effects on drag and lift that are critical to energy consumption and emissions, aircraft maneuverability, turbine noise, and vibration, etc. The proposed research is motivated by the observation that dermal denticles (tough scales) on shark skin show promising performance in reducing hydrodynamic drag. The ability of sharks’ unique skin in the fish world to dynamically respond to the flow offers a significant performance advantage over current flow control techniques. This fellowship aims at gaining a new fundamental understanding of the causal mechanisms associated with the drag reduction role of shark skin denticles and simultaneously advancing current numerical models for routine industrial design. With the support of an EPSCoR RII Track-4:NSF Fellowship, the PI will learn to simulate and analyze fluid-structure interactions and develop new models for numerical predictive tools through the training at the Center for Turbulence Research (CTR) at Stanford University. The fellowship will strengthen collaboration between the University of Mississippi and Stanford, and promote new economic development opportunities related to aeronautics, aerospace, and naval industries in the mid-south and in the State of Mississippi. The elastic anchoring of shark denticles enables them to bristle when subjected to the reversing separated flow that occurs at the onset of separation, thus hindering local separation. When flow is attached, denticles return to the non-bristled position and form a riblet-like texture to reduce friction drag. This motion leads to a flow-dependent anisotropic (or directional) function of the denticles that indicates a passive, flow-activated separation control technique. Current approaches, designed for stationary surface roughness, are insufficient to understand or predict the complex flows modulated by movable microstructures. The overarching goal of this fellowship is to support the PI’s training and collaborative research at the CTR. The training and research will focus on the cutting-edge fluid-structure interaction simulation methods and the development and validation of a novel wall model for the prediction of complex effects represented by surface microstructures. Specific objectives include: (i) to generate an unprecedented dataset of flows over movable anisotropic microstructures, (ii) to gain a new fundamental understanding about non-linear interactions, (iii) to synthesize the understanding to develop truly predictive models for drag and momentum flux. This RII Track-4:NSF fellowship will expand the PI’s research capacity and transform his career path towards a promising direction in the fluid-solid multi-physics system and reduced-order model development. The unique flow control techniques achieved by the flow-dependent anisotropic microstructure will be highly transformative to many other research areas in aerospace, agricultural, biomedical, energy, and environmental engineering where the application of structures with directional function is needed for the flow control process. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.