Effect of the blockage ratio on the flow in a channel with a built-in square cylinder

Turki, Saïd; Abbassi, H.; Nasrallah, Sassi Ben

doi:10.1007/s00466-003-0496-2

Cited by 76 publications

(71 citation statements)

References 15 publications

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“…For the shedding behind the large cylinder the dominating peak gives f = 0.34 Hz for the experiments and f = 0.38 Hz for the simulations corresponding to Strouhal numbers St LDV = fD/U ∞ ≈ 0.234 and St CFD ≈ 0.262 which can be considered to be in good agreement. For the shedding behind the smaller cylinder the simulation gives the same frequency as behind the large cylinder whereas the LDV gives a peak at f = 0.6 Hz which is more consistent with other studies [37][38][39] behind fully-circular stepped cylinders. For the shedding behind the step, the experiments yield two dominant peaks, one at f = 0.36 Hz, which should correspond to the shedding from the large cylinder and f = 0.6 Hz which corresponds to the shedding from the small one, whereas the simulation once again gives the same frequency as for the large cylinder, not capturing the dynamics of the small cylinder or the step.…”

Section: Vortex Sheddingsupporting

confidence: 89%

“…In addition, the effect of blockage on vortex shedding for the flow past a step cylinder can also be significant. Some previous studies [37,38,[40][41][42][43] have shown that the effect of channel blockage on vortex shedding for the flow past a step cylinder can also be significant as the channel blockage affects f, consequently influencing St. The increase of shedding frequency with the increase of the blockage ratios is evidently observed in these spectral results ( Figure 6).…”

Section: Vortex Sheddingsupporting

confidence: 50%

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Study the Flow behind a Semi-Circular Step Cylinder (Laser Doppler Velocimetry (LDV) and Computational Fluid Dynamics (CFD))

2017

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Laser Doppler Velocimetry (LDV) measurements, flow visualizations and unsteady Reynolds-Averaged Navier-Stokes (RANS) Computational Fluid Dynamics (CFD) simulations have been carried out to study the turbulent wake that is formed behind a semi-circular step cylinder at a constant flow rate. The semi-circular cylinder has two diameters, a so-called step cylinder. The results from the LDV measurements indicate that wake length and vortex shedding frequency varies with the cylinder diameter. This implies that a step cylinder can be used to attract fish of different size. By visualizations of the formation of a recirculation region and the well-known von Kármán vortex street behind the cylinder are disclosed. The simulation results predict the wake length and shedding frequency well for the flow behind the large cylinder but fail to capture the dynamics of the flow near the step in diameter to some extent and the flow behind the small cylinder to a larger extent when compared with measurements.

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Section: Vortex Sheddingsupporting

confidence: 89%

Section: Vortex Sheddingsupporting

confidence: 50%

Study the Flow behind a Semi-Circular Step Cylinder (Laser Doppler Velocimetry (LDV) and Computational Fluid Dynamics (CFD))

2017

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“…They investigated the effect of Reynolds number and shearing rate on drag forces and vortex-shedding. Turki et al [10] investigated the blockage ratio ( ) in their work. They showed that the data would be acceptable for ≤0.16 and would not be reliable for >0.25.…”

Section: Introductionmentioning

confidence: 99%

Experimental Study of Near Wake Flow Behind a Rectangular Cylinder

Shadaram¹,

Fard²,

Rostamy³

2008

American J. of Applied Sciences

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Abstract:The turbulence characteristics of the near wake flow behind a rectangular cylinder is investigated in a two-dimensional analysis using a hot-wire anemometer. The time-averaged and fluctuating components of the velocity are measured for a cylinder having various width-to-height (b h −1 ) ratios. The measurements are carried out in a low-speed wind tunnel. Data from hot-wire anemometer is collected by a data acquisition system. The results show that the turbulence intensity in the flow wake decreases as the width-to-height ratio of the cylinder increases. In addition, the characteristics of the flow field in a few sections are evaluated. Spectral analysis of the velocity signals is carried out for two different Reynolds numbers. The spectral analysis shows that Strouhal number remains nearly constant in high Reynolds numbers. The results of present experiments are in close agreement with the most widely accepted results in the literature.

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“…The effect of blockage was investigated numerically by Stansby and Slaouti (1993), Anagnostopoulos et al (1996), Behr et al (1995) and Turki et al (2003). It is shown that, increasing the blockage factor leads to high Strouhal number, drag coefficient and stagnation pressure.…”

Section: Introductionmentioning

confidence: 99%

Numerical Simulations of Flow around Square Cylinder Using an Iterative High Order Difference Scheme

Fard¹,

Ghadimi²,

Zamanian³

2013

JAC

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A time dependent two-dimensional numerical simulation of flow around a rectangular cylinder is conducted using a particular high order compact finite difference method. The current forth-order compact scheme is implemented for the simulation of flow around bluff bodies for the first time. This formulation offers a semiexplicit method for the solution of Navier-Stokes equations in stream function-vorticity form and based on a nine point difference scheme with uniform grid spacing. The main advantage of the suggested method is its fast convergence and high accuracy.The proposed numerical method combines the enhanced Fourni'e's forth order scheme with a semi-explicit formulation. By this combination, very accurate results can be obtained with a relatively coarse mesh in a short time. Uniform grids are applied with this high performance algorithm, and the accuracy of the scheme is proved using the benchmark problem of incompressible laminar flow around a rectangular cylinder at medium and high Reynolds numbers. Current results have good agreement with other numerical and experimental values. Generally, it is shown that, using the high order finite difference method demonstrates fairly competitive results for the current problem.

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Effect of the blockage ratio on the flow in a channel with a built-in square cylinder

Cited by 76 publications

References 15 publications

Study the Flow behind a Semi-Circular Step Cylinder (Laser Doppler Velocimetry (LDV) and Computational Fluid Dynamics (CFD))

Study the Flow behind a Semi-Circular Step Cylinder (Laser Doppler Velocimetry (LDV) and Computational Fluid Dynamics (CFD))

Experimental Study of Near Wake Flow Behind a Rectangular Cylinder

Numerical Simulations of Flow around Square Cylinder Using an Iterative High Order Difference Scheme

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