CAREER: Hydrodynamics of Adaptive Lifting Surfaces in Unsteady Flows: An Integrated Experimental and Analytical Study

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Unsteady flow fields are common in many underwater applications, such as during high sea conditions, in a propeller wake, during cooperative swimming or during tides, and waves. In such environments, hovering, station keeping, or performing any other dynamic maneuvers become extremely difficult for traditional autonomous underwater vehicles (AUVs) because they are typically designed with rigid hydrofoils within a fixed operational envelope. However, aquatic swimmers can aptly morph their fins and tails to control unsteady forces across all positions and orientations. Engineers can design highly maneuverable next-generation AUVs with bio-inspired morphing hydrofoils which can mimic such performance. But a major bottleneck has been the lack of knowledge of unsteady hydrodynamics that govern the fluid-structure interaction of such morphing lifting surfaces. Therefore, the principal aim of this project is to provide a deep understanding of the unsteady hydrodynamics of adaptive lifting surfaces. This project will also promote advanced education of marine hydrodynamics and underwater robotics amongst students at all level, including outreach activities at the Orlando Science Center and the Orange County Public Library.The goal of this proposal is to develop new research and educational paradigm that will reveal and generalize the physics of morphing lifting surfaces to optimize its performance while encountering transient wake-inflow conditions. An integrated experimental and analytical approach is proposed to study the non-linear fluid-structure interaction (FSI) of adaptive lifting surfaces in such unsteady flows. The central hypothesis is that shape morphing can dynamically balance the unsteady loads on such adaptive lifting surfaces by selectively tuning the hydro-elastic response in a transient wake-inflow. The specific objectives are: (a) Unravel the complex non-linear FSI response of adaptive underwater lifting surfaces in a range of unsteady flows; (b) Decipher the spatial and temporal features of the vorticity dynamics and surface pressure through the time-resolved realization of the 3D flow-field and surface pressure; (c) Discover the changes in the above non-linear FSI response when the dynamically deforming lifting surface is subjected to a spatially varying inflow caused by periodic vortical disturbances; (d) Develop analytical models by significantly advancing the existing potential-flow-based framework.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.