Computational fluid dynamics modeling patterns and force characteristics of flow over in-line four square cylinders

Song, Yidan; Zhu, Rui; Simon, Terrence W.; Xie, Gongnan

doi:10.2298/tsci170211035s

Cited by 5 publications

(2 citation statements)

References 26 publications

(30 reference statements)

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“…Eizadi et al (2022) analyzed the transitions in the wake of six circular obstacles placed inline at Re = 40 to 180 and G = 0.5 to 18. They concluded that wake transitions of multiple cylinders depend not only on Re but also on G. Song et al (2017) observed the flow patterns and force variations over four inline square cylinders by considering Re = 300 and G = 1.5 to 8. They reported that, when G < 3.5, CD mean values for the downstream cylinders increased sharply with increasing G. For G > 3.5, the CD mean values of the downstream cylinders decreased gradually with increasing G. Islam et al (2018) investigated different aspect ratio effects on the flow around three inline cylinders at Re = 150, AR = 0.25 to 3, and G = 0.5 to 7.…”

Section: Introductionmentioning

confidence: 99%

Analysis of the wake mechanism in external flow around tandem bluff bodies with different aspect ratios

Abbasi,

Ehsan,

Rahman

et al. 2024

Front. Mech. Eng.

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The interaction mechanism of external flow with two inline rectangular cylinders having different aspect ratios under the impact of gap spacing (G) is the subject of this research. The gap spacing between the cylinders was varied from 0.25 to 20 times their size. Both cylinders were vertically mounted, with the first having a higher aspect ratio than the second. The results revealed five distinct flow patterns under the influence of G: single slender body, shear layer reattachment, intermittent shedding, binary vortex street, and single-row vortex street. The mean pressure on both cylinders was found to vary due to changes in flow patterns. Both cylinders bore the same shedding frequency but had different pressure variations. The second cylinder placed in the wake of first experienced negative average drag force for some spacing values, while the first cylinder had positive average drag values for all chosen G. Due to the change in flow pattern from shear layer reattachment to intermittent shedding flow, the negative drag force on the second cylinder jumped to a positive drag. It was also observed that the rms values of drag and lift force coefficients, as well as their amplitudes for the second cylinder, were mostly higher than corresponding values for the first cylinder at all selected G. This study revealed that G = 4 and 8 are the critical gap spacing values due to sudden changes in fluid force parameters.

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Section: Introductionmentioning

confidence: 99%

Analysis of the wake mechanism in external flow around tandem bluff bodies with different aspect ratios

Abbasi,

Ehsan,

Rahman

et al. 2024

Front. Mech. Eng.

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show abstract

“…ey found well-known flow features such as in-phase vortex shedding, antiphase vortex shedding, and vortex shedding flow regimes, which are wellknown flow characteristics and observed mostly in case of two-cylinder arrangement. Song et al [19] studied numerically various flow regimes and force statistics for flow around four square cylinders in an inline square configuration using the finite volume method (FVM). ey systematically investigated the effect of spacing between the cylinders for Re � 300. e authors found that g * � 3.5 is the critical spacing and the flow regime changes from a bistable shielded flow regime to a vortex shedding flow regime by changing the values of g * from 1.5 to 8.…”

Section: Introductionmentioning

confidence: 99%

Numerical Investigation of Fluid Flow past Four Cylinders at Low Reynolds Numbers

Shafee

Ul-Islam

2021

Mathematical Problems in Engineering

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A numerical investigation on the effects of separation ratios and Reynolds numbers on the flow around four square cylinders in diamond arrangement has been carried out using the lattice Boltzmann method. The separation ratios between the cylinders vary from g ∗ = 1 to 15. The Reynolds numbers based on the diameter of the square cylinder and the inlet uniform inflow velocity are selected from Re = 80 to 160. The computations show that a total of five different flow regimes are observed over the selected ranges: single bluff-body, quasi-unsteady, chaotic flow, in-phase synchronized vortex shedding, and antiphase synchronized vortex shedding flow regimes. It is found that the flow features significantly depend on both the separation ratio and Reynolds number, with the former’s influence being more than the latter’s. We found that the critical spacing for four square cylinders in diamond arrangement for selected Reynolds numbers (80 ≤ Re ≤ 160) is in the range of 2 ≤ g ∗ ≤ 5. The results reveal that the presence of secondary cylinder interaction frequencies indicates that, for chaotic flow regime, the wake pattern is not stable and there is a strong interaction of gap flows and continuous change in the direction of shed vortices behind the cylinders. The effects of the g ∗ and Re on fluid forces, vortex shedding frequency, and flow separation have been examined in detail.

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Aerodynamics and Wake Flow Characteristics of a Four-Cylinder Cluster

Nguyen

Inam

Lasagna

et al. 2023

Flow Turbulence Combust

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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 $$2 \times 2$$ 2 × 2 aligned square cylinders, at a separation distance in streamwise and cross-wind directions equal to cylinder side length, and at Reynolds number $${Re}=22,000$$ Re = 22 , 000 based on the single cylinder side length D. The case at $$0^\circ$$ 0 ∘ 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 $$45^\circ$$ 45 ∘ , 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.

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Computational fluid dynamics modeling patterns and force characteristics of flow over in-line four square cylinders

Cited by 5 publications

References 26 publications

Analysis of the wake mechanism in external flow around tandem bluff bodies with different aspect ratios

Analysis of the wake mechanism in external flow around tandem bluff bodies with different aspect ratios

Numerical Investigation of Fluid Flow past Four Cylinders at Low Reynolds Numbers

Aerodynamics and Wake Flow Characteristics of a Four-Cylinder Cluster

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