Qualitative and Quantitative Study of the Flow Physics in the Vicinity of an Oscillating Plate in Viscous Fluids
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In this thesis, we study the fluid-structure interaction problem of a submerged rigid plate undergoing harmonic oscillations in a still, Newtonian, viscous fluid. We conduct a comprehensive qualitative and quantitative analysis of the problem for a broad range of values of the parameters of oscillation, including frequency and amplitude, to study the fluid-structure interaction mechanisms responsible for the hydrodynamic forces acting on the plate. The primary objective of this study is to understand the effect of the parameters of oscillation on the resulting flow pattern and analyze their relation to the hydrodynamic forces. More specifically, we classify the flow patterns into different regimes and characterize their unique features. Such classification is based on qualitative properties of the flow. An extensive experimental study of the forces acting on the plate for each particular regime is performed to establish quantitative properties of each flow regime as well. Specifically, this study employs two experimental techniques, namely Particle Image Velocimetry (PIV) and direct force measurement load cell, to estimate the hydrodynamic forces. These measurements help elucidate the effect of qualitative dynamical aspects, such as the presence of vortices, on the nature of the hydrodynamic loading. Further, a comparison of experimental results against predicted values from numerical and semi-analytical models is reported to demonstrate the validity of our approach and, simultaneously, experimentally validate numerical approaches discussed in the literature. Fundamental findings from this work have direct relevance to various engineering applications, specifically in the field of energy harvesting devices, biomimetic robotic propulsion system, and micro-mechanical oscillation-based sensors and actuators.