Experimental and numerical modeling of unsteady fluid-structure interactions occurring across various interfaces in environmental flows

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According to the recent report of Natural Resources Canada, the estimated energy potential of the Canadian rivers for in-stream (hydrokinetic) energy is ~340 GW. To harvest this energy, various scales of turbine systems have been developed and tested. These devices operated either standalone or in arrays and exhibit many economic, technical and environmental impact challenges. Furthermore, most rivers typically flow at a velocity lower than 1 m/s, which is not suitable for the efficient operation of the rotary turbine. A new flow-induced vibration (FIV) energy harvesting based on low-speed flows can complement the existing technologies and offer better flexibility for small, remote communities. This proposal explores the potential of FIV as a novel energy source where the hydrokinetic river energy can be utilized as a part of an affordable and environmentally friendly solution to meet the growing energy demands. Fluid--structure interaction (FSI) is a common phenomenon in engineering caused by the alternating vortices formed in the aft body of the slender structure shed downstream with a coherent but varied flow pattern. These vortices create vortex-induced forces on the body, which are periodic, resulting from the phenomenon of flow -induced vibration (FIV). In most practical applications, vortex formation is responsible for FIV, including vortex-induced vibration (VIV), generally of the isolated cylinder, wake- induced vibration (WIV) of multiple circular cylinders, as well as the galloping for complicated cylinders (such as cylinder with attachments and slots). Researchers have primarily studied the suppression of FIV to avoid excessive vibrations leading to failure. In contrast, in the design of energy harvesting systems, the vibrational energy due to FIV must be maximized to increase energy conversion efficiency. A novel experimental and numerical research program is proposed to better understand the underlying flow physics of a highly coupled fluid-structure system, where a variety of flow conditions and structural attributes can considerably alter the FIV response. The proposal focuses on studying the FSI of single and multiple oscillating (flexible) bodies in steady and unsteady flow conditions. Information from vibration response, coherent structures, and wake dynamics will allow developing optimal flow strategies that are essential for engineers to address. The flow cases identified in the short-term objectives of this proposal are more complex, as they investigate FIVs of non--circular cylinders and multi--body array configurations, including effects of the inflow, and free surface (shallow and oscillatory wave flows) to study the feasibility of energy exchange. These aspects are seldom addressed in previous research. The proposed research will explore and facilitate the development of more effective modeling tools based on machine learning algorithms to bridge the gap between experimental and computational fluid dynamics.