Drag Reduction on a Square Cylinder using Multiple Detached Control Cylinders

Shams-ul-Islam,; Manzoor, Raheela; Khan, Umar; Nazeer, Ghazala; Hassan, Sehrish

doi:10.1007/s12205-017-0239-0

Cited by 11 publications

(14 citation statements)

References 32 publications

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“…It can be seen from Figure 5a-c that the shed vortices are observed only at the downstream location of the channel and the strength of shed vortices for small size of control rods (i.e., d1 = 4 is maximum as compared to d1 = 16 for g = 4). This flow mode is also observed at (g, d1) = (3, 12), (3,16), (3,20), (4,4), and (4,20). Igarashi and Suzuki [29] also investigated this flow behavior and named this mode as with reattachment and roll up flow for three circular rods.…”

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

confidence: 55%

“…The fourth flow mode was observed at (g, d1) = (1, 12), (2,12), and (2,16). The vorticity contours of steady flow mode are shown in Figure 6a,b.…”

Section: Steady Flow (Sf) Modementioning

confidence: 93%

“…Temporal histories of Cd and Cl are presented in Figure 4a . Here we only discuss the cases (g, d1) = (1, 8), (1,16), and (2, 20) (see Figure 4a,b). As the gap spacing and size of both the control rods are changed, the flow behaves very differently, and it is no longer SBB flow mode.…”

Section: Single Bluff Body (Sbb) Flow Modementioning

confidence: 99%

“…The third existing flow mode is called rolled up shear layer reattachment (RSLR) flow mode, that was investigated at (g, d1) = (3, 4), (4,16), and (5, 4) (see Figure 5a-c). It was noticed that when the gap increased from g = 2 to 5 for different sizes of control rods, then fluid entered in both gaps.…”

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

confidence: 99%

“…Islam et al [15] observed a reduction in C dmean of 8.3%, when two control rods were placed at an upstream distance, 51% when the two control rods were placed at a downstream distance and 50.8% when four control rods were placed upstream and downstream of a square rod. Islam et al [16] placed three control rods upstream and three downstream of a main rod and studied the effect of Re and g. They found weakly vortex shedding, and steady and strongly-induced vortex shedding flow modes. They examined that the vortex shedding suppression was dependent on both g and Re, but the latter one was more effective.…”

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: 55%

“…The fourth flow mode was observed at (g, d1) = (1, 12), (2,12), and (2,16). The vorticity contours of steady flow mode are shown in Figure 6a,b.…”

Section: Steady Flow (Sf) Modementioning

confidence: 93%

Section: Single Bluff Body (Sbb) Flow Modementioning

confidence: 99%

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

confidence: 99%

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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Investigation of Optimum Conditions for Flow Control Around Two Inline Square Cylinders

et al. 2021

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Numerical study of reduction of fluid forces acting on a square cylinder using a control plate

Zia-ul-Islam

Shams-ul-Islam

Zhou

et al. 2021

J Braz. Soc. Mech. Sci. Eng.

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A numerical study on the effects of control plate on the fluid force reduction on a square cylinder has been carried out using lattice Boltzmann method where a configuration of a square cylinder with upstream control plate is studied. In the present computations we have studied the important flow characteristics for 0.1 ≤ l/w ≤ 1 and 1 ≤ g/D ≤ 10. The effects of the l/w and g/D on force reduction, flow separation and vortex shedding frequency have been studied with Reynolds number focused on 150. Vorticity structures, vortex shedding frequency and fluctuating forces and time-mean are presented and discussed. It was found that considerable change in the wake structure and fluid forces depending on the values of l/w and g/D. The numerical results show that there exists an optimum position where the force coefficients acting on the main square cylinder attains their minimum values. At the optimum position, the mean drag coefficient is reduced by 139.3%. Four different flow regimes were identified in this study at different g/D for selected range of l/w. The negative values of drag coefficient for the main square cylinder are also found for different combinations of l/w and g/D.

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Drag Reduction on a Square Cylinder using Multiple Detached Control Cylinders

Cited by 11 publications

References 32 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

Investigation of Optimum Conditions for Flow Control Around Two Inline Square Cylinders

Numerical study of reduction of fluid forces acting on a square cylinder using a control plate

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