Lattice Boltzmann Study of Wake Structure and Force Statistics for Various Gap Spacings Between a Square Cylinder with a Detached Flat Plate

Islam, Saiful; Rahman, Hamid; Abbasi, Waqas Sarwar; Shahina, T.

doi:10.1007/s13369-015-1648-3

Cited by 32 publications

(16 citation statements)

References 18 publications

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“…Igarashi and Suzuki [29] also investigated this flow behavior and named this mode as with reattachment and roll up flow for three circular rods. This kind of flow mode was also found by Islam et al [13] for flow past a square rod with a detached control plate.…”

Section: Rolled Up Shear Layer Reattachment (Rslr) Flow Modesupporting

confidence: 80%

“…They examined that the length of the control plate and its position play an important role in controlling the flow behind the main rod. Islam et al [13] numerically studied different flow regimes for flow over a square rod with a downstream control plate at Re = 150 and g = 0-11. They classified the flow into extended-body (0 ≤ g ≤ 1.53), reattachment (1.9 ≤ g ≤ 4), and fully developed (4.8 ≤ g ≤ 11) flow regimes.…”

Section: Introductionmentioning

confidence: 99%

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Numerical Simulation of Drag Reduction on a Square Rod Detached with Two Control Rods at Various Gap Spacing via Lattice Boltzmann Method

et al. 2020

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Numerical simulations are performed to examine the effect of size of control rods (d1) and spacing ratio (g) on flow around a square rod with upstream and downstream control rods aligned in-line using the lattice Boltzmann method (LBM). The Reynolds number (Re) is fixed at Re = 160, while the spacing between the main rod and control rods is taken in the range 1 ≤ g ≤ 5 and the size of the control rod is varied between 4 and 20. Seven different types of flow mods are observed in this study at different values of g and d1. Variation in force statistics, like mean drag coefficient (Cdmean), Strouhal number (St), root mean square values of drag (Cdrms) and lift coefficients (Clrms), and percentage reduction in mean drag coefficient is discussed in detail. It was examined that vortex shedding completely suppressed at (g, d1) = (1, 12), (2, 12), and (2, 16) where steady flow mode exists. Moreover, it was found that at large gap spacing, where g = 5, the effect of control rods on the main rod vanishes. Due to this strong vortex shedding produced and as a result, maximum value of Cdmean is found at (g, d1) = (5, 8). The negative values of mean drag force are also observed at some gap spacing and size of control rods are due to the effect of thrust. Furthermore, the maximum percentage reduction in Cdmean is 121%, found at (g, d1) = (2, 20).

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Section: Rolled Up Shear Layer Reattachment (Rslr) Flow Modesupporting

confidence: 80%

Section: Introductionmentioning

confidence: 99%

Numerical Simulation of Drag Reduction on a Square Rod Detached with Two Control Rods at Various Gap Spacing via Lattice Boltzmann Method

et al. 2020

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“…Gera et al [6] numerically analyzed the onset of vortex shedding from a square cylinder under the effect of Re in the range 50-250. More work about the flow characteristics around single cylinder can be found in [7][8][9][10].…”

Section: Introductionmentioning

confidence: 99%

Transition from steady to unsteady state flow around two inline cylinders under the effect of Reynolds numbers

Abbasi

Islam

2018

J Braz. Soc. Mech. Sci. Eng.

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Numerical computations are carried out to analyze the transition in flow states around two inline square cylinders under the effect of Reynolds numbers (Re). For this analysis, Re is varied from 1 to 110 at a fixed spacing ratio g = 3.5. The results are presented in the form of vorticity contours, streamline graphs, temporal histories of drag and lift coefficients and power spectrum of lift coefficients. Also the physical parameters like average drag coefficient, Strouhal number and the rootmean-square values of drag and lift coefficients are presented as a function of Re. Three different states of flow are found in this study by systematically varying Re: (a) steady state, (b) quasi-unsteady state, and (c) unsteady state. The points of separation and reattachment of shear layers depend on Re. This study shows that the values of physical parameters strongly depend on flow states and change their behavior when flow mode changes from one state to another. A significant reduction in the values of flow induced forces found due to the presence of two cylinders in the flow field when compared to single cylinder values. The results of the present study are also compared with the available data of other researchers and found to be in good agreement.

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“…Here we include a short description of the numerical method and refer the reader to our previously [34][35][36][37] reported work for detailed discussion. The macroscopic fluid variables such as density and velocity are computed from the microscopic particles movement on a lattice from the main steps: streaming and collision.…”

Section: A Lattice Boltzmann Methods and Problem Descriptionmentioning

confidence: 99%

A computational study of flow past three unequal sized square cylinders at different positions

et al. 2017

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The flow past three unequal sized side-by-side square cylinders placed in different vertical configurations is investigated numerically using the lattice Boltzmann method for the Reynolds number Re = 160 and different values of the gap spacing between the cylinders, g, (ranging between 0.5 and 5). The present study is devoted to systematic investigation of the effects of cylinders position on the flow patterns. The reported results reveal that the flow patterns change significantly by the variation of cylinders configuration. Depending on the cylinders positions we observed; chaotic, base bleed, binary vortex street, modulated synchronized, inphase vortex shedding, antiphase vortex shedding, and in-antiphase vortex shedding flow patterns. The characteristics of the flow patterns are discussed with the aid of time history analysis of drag and lift coefficients, power spectra analysis of lift coefficients and vorticity contours visualization. The study also includes a detailed discussion on the aerodynamic forces, such as mean drag coefficient, Strouhal number and root-mean-square values of drag and lift coefficients. Our results show that the flow patterns behind three unequal cylinders are distinctly different compared to the flow past equisized square cylinders placed side-by-side. In chaotic flow pattern the secondary cylinder interaction frequency plays an important role especially at the second, third and fourth configurations for all gap spacings. At larger gap spacings for the first and sixth configurations, the primary vortex shedding frequency plays a dominant role and the jet effect almost diminishes between the cylinders.

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Lattice Boltzmann Study of Wake Structure and Force Statistics for Various Gap Spacings Between a Square Cylinder with a Detached Flat Plate

Cited by 32 publications

References 18 publications

Numerical Simulation of Drag Reduction on a Square Rod Detached with Two Control Rods at Various Gap Spacing via Lattice Boltzmann Method

Numerical Simulation of Drag Reduction on a Square Rod Detached with Two Control Rods at Various Gap Spacing via Lattice Boltzmann Method

Transition from steady to unsteady state flow around two inline cylinders under the effect of Reynolds numbers

A computational study of flow past three unequal sized square cylinders at different positions

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