Aerodynamics and wake flow characteristics of a four-cylinder cluster
Aerodynamics and wake flow characteristics of a four-cylinder cluster
The aerodynamic behaviour and wake flow of a cluster of two-dimensional sharp-edged bluff bodies exhibits extremely complex unsteady phenomena in both near and far fields. Due to the high cost of wind-tunnel experiments and numerical simulations, a complete understanding of wake flows and a description of their characteristics are lacking. This paper presents large-eddy simulations (LES) in different flow/wind directions for a cluster of $2 \times 2$ aligned square cylinders, at a separation distance in streamwise and cross-wind directions equal to cylinder side length, and at Reynolds number ${Re}=22,000$ based on the single cylinder side length $D$. The case at $0\degree$ incidence shows an evident channel-type flow in the along-wind street/gap, and at its exit an irregularly pulsing jet with an intense shedding of large vortices. The wavelet analyses of the side force/lift coefficient and instantaneous velocities in the wake show that the characteristic length and time scales of the large vortical structures in the far-field wake are close to the cluster size $2D$; this is the so called `cluster effect'. The cluster effect increases monotonically as the flow incidence angle increases. At a large incidence angle in the near-field wake, the cylinder-scale flow structures are much weaker compared to the cluster-scale structures. At the incidence angle of $45\degree$, the overall wake flow and the aerodynamic characteristics are well scaled by the scale approximately equal to $2D$. Nevertheless, the interaction between cylinders significantly affects the aerodynamics performance of the individual cylinders. The drag and lift coefficients of the individual cylinders differ substantially from each other in the cluster, and are significantly different from observations on a single isolated cylinder too.
Cylinder cluster, LES, Lift coefficient, Square cylinder, Vortex shedding, Wake characteristics, Wake interaction
1091-1115
Nguyen, Cung
c3d1ec16-957b-4130-aa1a-83a34ba8e3b5
Inam, Saad
ab826234-0586-43f6-a287-d2c66e989816
Lasagna, Davide
0340a87f-f323-40fb-be9f-6de101486b24
Xie, Zheng-Tong
98ced75d-5617-4c2d-b20f-7038c54f4ff0
1 May 2023
Nguyen, Cung
c3d1ec16-957b-4130-aa1a-83a34ba8e3b5
Inam, Saad
ab826234-0586-43f6-a287-d2c66e989816
Lasagna, Davide
0340a87f-f323-40fb-be9f-6de101486b24
Xie, Zheng-Tong
98ced75d-5617-4c2d-b20f-7038c54f4ff0
Nguyen, Cung, Inam, Saad, Lasagna, Davide and Xie, Zheng-Tong
(2023)
Aerodynamics and wake flow characteristics of a four-cylinder cluster.
Flow Turbulence and Combustion, 110 (4), .
(doi:10.1007/s10494-023-00419-0).
Abstract
The aerodynamic behaviour and wake flow of a cluster of two-dimensional sharp-edged bluff bodies exhibits extremely complex unsteady phenomena in both near and far fields. Due to the high cost of wind-tunnel experiments and numerical simulations, a complete understanding of wake flows and a description of their characteristics are lacking. This paper presents large-eddy simulations (LES) in different flow/wind directions for a cluster of $2 \times 2$ aligned square cylinders, at a separation distance in streamwise and cross-wind directions equal to cylinder side length, and at Reynolds number ${Re}=22,000$ based on the single cylinder side length $D$. The case at $0\degree$ incidence shows an evident channel-type flow in the along-wind street/gap, and at its exit an irregularly pulsing jet with an intense shedding of large vortices. The wavelet analyses of the side force/lift coefficient and instantaneous velocities in the wake show that the characteristic length and time scales of the large vortical structures in the far-field wake are close to the cluster size $2D$; this is the so called `cluster effect'. The cluster effect increases monotonically as the flow incidence angle increases. At a large incidence angle in the near-field wake, the cylinder-scale flow structures are much weaker compared to the cluster-scale structures. At the incidence angle of $45\degree$, the overall wake flow and the aerodynamic characteristics are well scaled by the scale approximately equal to $2D$. Nevertheless, the interaction between cylinders significantly affects the aerodynamics performance of the individual cylinders. The drag and lift coefficients of the individual cylinders differ substantially from each other in the cluster, and are significantly different from observations on a single isolated cylinder too.
Text
FTaC_4cylinders_2022
- Accepted Manuscript
Text
s10494-023-00419-0
- Version of Record
More information
Submitted date: 18 October 2022
Accepted/In Press date: 12 April 2023
e-pub ahead of print date: 26 April 2023
Published date: 1 May 2023
Additional Information:
The study presented in this paper is part of the UK Engineering and Physical Sciences Research Council (EPSRC)-funded project FUTURE (Grant No. EP/V010514/1). High performance computer systems at the University of Southampton, and the UK National Supercomputing system Archer2 via the UK Turbulence Consortium awards (Grant Nos. EP/D44073/1, EP/G06958/1, Project Code e01), were used for the massive compuational work.
Keywords:
Cylinder cluster, LES, Lift coefficient, Square cylinder, Vortex shedding, Wake characteristics, Wake interaction
Identifiers
Local EPrints ID: 471600
URI: http://eprints.soton.ac.uk/id/eprint/471600
ISSN: 1386-6184
PURE UUID: e596fb51-3fd8-4726-b9d9-41192cfe4666
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Date deposited: 22 Jan 2025 17:43
Last modified: 23 Jan 2025 02:46
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Contributors
Author:
Cung Nguyen
Author:
Saad Inam
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