Bluff Body Overflow and Drag Reduction Control

Zhao, Min

doi:10.1007/978-981-33-6526-1_3

Cited by 1 publication

(1 citation statement)

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“…Meanwhile, the asymmetric vortex shedding would induce large unsteady side forces that, in turn, may lead to structural vibrations if the body is flexibly mounted. Therefore, for reducing drag and suppressing VIV, controls of vortex shedding characteristics of flow over a bluff body have attracted significant attention in the past (Zhao 2021). Many flow control techniques have been proposed in (i) passive form and (ii) active form.…”

Section: Introductionmentioning

confidence: 99%

Dynamics of a rigid-flexible coupling system in a uniform flow

et al. 2022

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Dynamics of two-dimensional flow past a rigid flat plate with a trailing closed flexible filament acting as a deformable afterbody are investigated numerically by an immersed boundary-lattice Boltzmann method for the fluid flow and a finite element method for the filament motion. The effects of Reynolds number ( $Re$ ) and length ratio ( $Lr$ ) on the flow patterns and dynamics of the rigid-flexible coupling system are studied. Based on our numerical results, five typical state modes have been identified in $Lr\unicode{x2013}Re$ plane in terms of the filament shape and corresponding dynamics, i.e. static deformation, micro-vibration, multi-frequency flapping, periodic flapping and chaotic flapping modes, respectively. Benefiting from the passive flow control by using the flexible filament as a deformable afterbody, the coupled system may enjoy a significant drag reduction (up to $22\,\%$ ) compared with bare plate scenarios ( $Lr=1$ ). Maximum drag reduction achieved at $L_{c,{min}} \in [1.8, 2]$ is often accompanied by the onset of the system state transition. The flow characteristic and its relation to the change in hydrodynamic drag are further explored in order to reveal the underlying mechanisms of the counterintuitive dynamical behaviour of the coupled system. The scaling laws for the form drag and the friction drag, which arise from the pressure and viscous effects, respectively, are proposed to estimate the overall drag acting on the system. The results obtained in the present study may shed some light on understanding the dynamical behaviour of rigid-flexible coupling systems.

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Section: Introductionmentioning

confidence: 99%