Numerical Computations for Flow Patterns and Force Statistics of Three Rectangular Cylinders

Rahman, Hamid; Shams-ul-Islam,; Abbasi, Waqas Sarwar; Manzoor, Raheela; Amin, Fazle; Alam, Zeeshan

doi:10.1155/2021/9991132

Cited by 2 publications

(5 citation statements)

References 26 publications

(37 reference statements)

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“…Figure 8B presents the variation of St of both cylinders with G. Both cylinders have same St for all G, indicating that the vortices shed from both cylinders with same frequency notwithstanding whether both cylinders have different ARs. Rahman et al (2021) also found similar behavior in St for flow past three rectangular cylinders. Initially for G = 0.25 to 0.75, St shows increasing behavior.…”

Section: Force Statisticssupporting

confidence: 58%

“…The flow around two tandem rectangular cylinders with distinct aspect ratios was simulated at Re = 100 by considering different values of G progressively varying from 0.25 to 20. From previous studies, we can conclude that the flow structure mechanism around multiple rectangular cylinders appears to be a complicated phenomenon that depends on several parameters, including Re, G, and AR (Islam et al, 2018;Rahman et al, 2021). In the current study, the resulting flow regimes are specified into different patterns in terms of the creation of different shape vortices, wake structure mechanism, and the behavior of shear layers detaching from cylinder corners and interacting with each other.…”

Section: Resultsmentioning

confidence: 68%

“…For example, the particles with distribution functions f 7 , f 4 , and f 8 streaming toward the lower wall bounce back as f 7 = f 5 , f 4 = f 2 , and f 8 = f 6 . A similar procedure was also adopted for other directions for fluid particles hitting the solid walls (Rahman et al, 2021). Although the geometry considered in the current study has smooth boundaries, LBM is also a suitable choice for curved or moving boundaries (Tao et al, 2018;Marson et al, 2021).…”

Section: Problem Statementmentioning

confidence: 99%

“…Therefore, we considered the 20-point grid for analysis for this study. This grid size follows recommendations based on lattice Boltzmann simulations for both single and multiple objects (Islam et al, 2018;Rahman et al, 2021). Note that the uniform meshing (Δx Δt 1) is selected in the whole computational domain because the standard LBM considers such meshing for simulations without any need to use external mesh generators (Perumal et al, 2012).…”

Section: Grid Independencementioning

confidence: 99%

“…They observed that, at all G, the CL rms of all cylinders decreased with increasing AR. Rahman et al (2021) numerically computed the…”

Section: Introductionmentioning

confidence: 99%

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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: Force Statisticssupporting

confidence: 58%

Section: Resultsmentioning

confidence: 68%

Section: Problem Statementmentioning

confidence: 99%

Section: Grid Independencementioning

confidence: 99%

“…They observed that, at all G, the CL rms of all cylinders decreased with increasing AR. Rahman et al (2021) numerically computed the…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

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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Rectangular Cylinder Orientation and Aspect Ratio Impact on the Onset of Vortex Shedding

Tahir,

Abbasi,

Rahman

et al. 2023

Mathematics

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Rectangular cylinders have the potential to provide valuable insights into the behavior of fluids in a variety of real-world applications. Keeping this in mind, the current study compares the behavior of fluid flow around rectangular cylinders with an aspect ratio (AR) of 1:2 or 2:1 under the effect of the Reynolds number (Re). The incompressible lattice Boltzmann method is used for numerical computations. It is found that the flow characteristics are highly influenced by changes in the aspect ratio compared to the Reynolds number. The flow exhibits three different regimes: Regime I (steady flow), Regime II (initial steady flow that becomes unsteady afterward), and Regime III (completely unsteady flow). In the case of the cylinder with an aspect ratio of 2:1, vortex generation, variation in drag, and the lift coefficient occur much earlier at very low Reynolds numbers compared to the cylinder with an aspect ratio of 1:2. For the cylinder with an aspect ratio of 1:2, the Reynolds number ranges for Regimes I, II, and III are 1 ≤ Re ≤ 120, 121 ≤ Re ≤ 144, and 145 ≤ Re ≤ 200, respectively. For the cylinder with an aspect ratio of 2:1, the Reynolds number ranges for Regimes I, II, and III are 1 ≤ Re ≤ 24, 25 ≤ Re ≤ 39, and 40 ≤ Re ≤ 200, respectively. The cylinder with an aspect ratio of 1:2 is found to have the ability to stabilize the incoming flow due to its extended after-body flatness. Generally, it has been found that a cylinder with an AR of 2:1 is subjected to higher pressures, higher drag forces, higher curvatures of cross-flow rotations, and higher amplitudes of flow-induced drag, as well as higher lift coefficients and lower shedding frequencies, compared to cylinders with an AR of 1:2. In Regime III, elliptic and vertically mounted airfoil-like flow structures are also observed in the wake of the cylinders.

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Numerical Computations for Flow Patterns and Force Statistics of Three Rectangular Cylinders

Cited by 2 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

Rectangular Cylinder Orientation and Aspect Ratio Impact on the Onset of Vortex Shedding

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