Steady flow around an inclined torus at low Reynolds numbers: Lift and drag coefficients

Yu, Peng, Lu, Ruixin, He, Wei ORCID: 0000-0002-2633-6114 and Li, Larry KB (2018) Steady flow around an inclined torus at low Reynolds numbers: Lift and drag coefficients. Computers & Fluids, 171. pp. 53-64.

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Abstract

The steady flow around an inclined torus has received little attention in the hydrodynamics literature, despite being relevant to many engineering and biological processes, such as the sedimentation of fluidized particles and the motion of natural micro-swimmers. In this study, we perform three-dimensional direct numerical simulations of the flow around an inclined torus over a range of aspect ratios Image 1, inclination angles (0 ⩽ θ ⩽ 90°) and Reynolds numbers (10 ⩽ Re ⩽ 50), with a focus on the steady flow regime preceding the onset of vortex shedding. For a fixed Re, we find that as the torus inclines from a flow-normal orientation (θ=0∘) to a flow-parallel orientation (θ=90∘), the drag coefficient (CD) decreases monotonically, while the lift coefficient (CL) first increases from zero, reaches a maximum at 40° ⩽ θ ⩽ 50° and then returns to zero owing to top-down symmetry at full inclination. The decrease in CD with θ is caused by a decrease in the pressure drag, with almost no change in the viscous drag. The variation in CL with θ is caused by the pressure lift dominating the viscous lift. With increasing Re, the overall trends in CD and CL remain qualitatively unchanged but their quantitative values decrease. Compared with the effects of θ and Re, those of Image 2 are relatively weak for the specific flow conditions examined here. We conclude by performing a nonlinear regression analysis to generate curve fits for CD and CL in terms of Image 2, θ and Re.

Item Type:	Article
Additional Information:	publisher: Elsevier articletitle: Steady flow around an inclined torus at low Reynolds numbers: Lift and drag coefficients journaltitle: Computers & Fluids articlelink: https://doi.org/10.1016/j.compfluid.2018.05.017 content_type: article copyright: © 2018 Elsevier Ltd. All rights reserved.
Uncontrolled Keywords:	Wakes, Bluff-body flows, Torus, Recirculation zone, Direct numerical simulations
Depositing User:	Symplectic Admin
Date Deposited:	05 Feb 2019 15:06
Last Modified:	19 Jan 2023 01:05
DOI:	10.1016/j.compfluid.2018.05.017
Related URLs:	Author Publisher
URI:	https://livrepository.liverpool.ac.uk/id/eprint/3032254