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Session: Flow induced vibrations
Session starts: Tuesday 18 June, 09:40
Presentation starts: 09:40
Room: Room 1.3

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Chandan Bose (University of Birmingham)
Grigorios Dimitriadis (University of Liège)

Abstract:
The characterization of nonlinear aeroelastic instabilities under undisturbed freestream conditions has been the subject of continued interest in the existing literature. However, the effect of upstream flow disturbances on the dynamic behaviour of aeroelastic systems has remained relatively unexplored. Recent studies have mostly considered the temporal fluctuation of the inflow and reported that the aeroelastic response dynamics strongly depends on the inflow conditions [1]. In practice, aeroelastic systems are often subjected to spatio-temporal flow disturbances; one such situation is when an aeroelastic system encounters a vortical wake [2]. This abstract proposes to systematically investigate the influence of a vortical wake coming from an upstream bluff-body on the response dynamics of a canonical pitch-plunge aeroelastic system. To this end, the flow-induced vibration of a two degrees-of-freedom (2-DoF) airfoil section in the wake of an upstream bluff body is simulated using the open-source library OpenFOAM. The present fluid-structure interaction framework is developed by coupling a Navier-Stokes solver with the structural model using a partitioned weak coupling approach. The unsteady flow-field is simulated at a Reynolds number of 2 × 10^4 using the incompressible Navier-Stokes solver - overPimpleDyMFoam. The structural counterpart comprises a stationary bluff body situated upstream of the 2-DoF pitch-plunge aeroelastic system. The elastically-mounted airfoil motion is simulated using the six-degrees-of-freedom rigid body motion solver available in OpenFOAM. The Newmark time-integration scheme is used to solve the structural equations. The oscillation amplitude of an aeroelastic system, situated in the primary wake formation region of an upstream bluff-body, can attain a considerably high value if the coupled system frequency locks in with the shedding frequency of the bluff-body, thus offering significant potential for energy extraction. The primary focus is to study the effect of the oscillating velocity field due to periodic vortex shedding behind the upstream bluff body on the flutter characteristics of the aeroelastic system and the underlying wake-structure interactions. The findings of this study can benefit the efficient design of biologically inspired propulsion systems and energy harvesters. References: 1. Dominique C Poirel and Stuart J Price. Structurally nonlinear fluttering airfoil in turbulent flow. AIAA Journal, 39(10):1960–1968, 2001. 2. Zachary N Gianikos, Benjamin A Kirschmeier, Ashok Gopalarathnam, and Matthew Bryant. Limit cycle characterization of an aeroelastic wing in a bluff body wake. Journal of Fluids and Structures, 95:102986, 2020.