Experimental investigation on the aerodynamic behavior of square cylinders with rounded corners

Carassale, Luigi; Freda, Andrea; Marrè-Brunenghi, Michela

doi:10.1016/j.jfluidstructs.2013.10.010

Cited by 147 publications

(67 citation statements)

References 17 publications

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“…the wider the wake is, the more slowly the vortex sheds, which will be discussed later. The same conclusion is drawn by Tamura and Miyagi, [5] Carassale et al [6] and Kurata et al [8] After corner modification, the length of recirculation region increases, as listed in the third column of Table 1. Time-averaged streamlines for two cases are shown in Figure 2.…”

Section: Resultssupporting

confidence: 75%

“…Tamura and Miyagi [5] revealed that the separated shear layers approached the side surface of square cylinders with corner-cutting and corner-rounding, thus promoting reattachment and reducing drag forces through their experiment. Carassale et al [6] also reached the same conclusion by rounding the corners of square cylinder. Yamagishi et al [7] investigated the flow over square cylinders with chamfered corners, rounded corners and stepped corners, and found that when the chamfered corners were 10% of the side length, a significant drag reduction of 30% was achieved as a result of the smallest separation region.…”

Section: Introductionmentioning

confidence: 62%

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Experimental investigation on the flow over normal flat plates with various corner shapes

Feng

Wang

2015

Journal of Turbulence

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The influence of corner modification on the flow over normal flat plates is experimentally investigated in a water tunnel. Particle image velocimetry measurement is performed at Re = 2240 based on the width of the plate. Besides the flat plate with sharp edges, others with chamfered corners, rounded corners and stepped corners at the windward side are studied. Although the flat plate is very thin compared with square cylinders, corner modification can also achieve a significant drag reduction. The mechanism for the drag reduction is explored based on the solid analysis of the vortical structures and the statistical parameters. With corner modification, the strength and the scale of the vortex are decreased, while the formation of the vortex is postponed, resulting in a weakened vortex-interaction process. Thus, the fluctuation intensity of the wake is weakened, the wake width is narrowed down with the recirculation region elongated, and the vortex shedding frequency becomes higher. These modifications interpret well how the drag of a normal plate could be reduced, which is confirmed by the drag estimation from the wake profiles.

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Section: Resultssupporting

confidence: 75%

Section: Introductionmentioning

confidence: 62%

Experimental investigation on the flow over normal flat plates with various corner shapes

Feng

Wang

2015

Journal of Turbulence

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“…By rounding the corners of a square cylinder with a small radius of curvature, the formation of the shedding vortices are initialized further downstream away from the cylinder compared with both the circular and square geometries, and results in the streamwise expansion of the recirculation bubbles. Similar numerical and experimental studies are also performed for the fully developed turbulent wake flow downstream of a partially rounded cylinder at Re∼O(10 4 −10 6 ) [20][21][22]. It can be concluded from these studies that the aerodynamic characteristics of the cylinder and wake flow pattern are significantly affected by the cylinder geometry, more specifically, the corner radius.…”

Section: Introductionmentioning

confidence: 73%

Effect of Corner Radius in Stabilizing the Low-Re Flow Past a Cylinder

Zhang

Samtaney

2017

Journal of Fluids Engineering

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We perform global linear stability analysis on low-Re flow past an isolated cylinder with rounded corners. The objective of the present work is to investigate the effect of cylinder geometry (corner radius) on the stability characteristics of the flow. Our investigation sheds light on new physics that the flow can be stabilized by partially rounding the cylinder in the critical and weakly supercritical flow regimes. The flow is first stabilized and then gradually destabilized as the cylinder varies from square to circular geometry. The sensitivity analysis reveals that the variation of stability is attributed to the different spatial variation trends of the backflow velocity in the near- and far-wake regions for various cylinder geometries. The results from the stability analysis are also verified with those of the direct simulations, and very good agreement is achieved.

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“…This may be a combined effect of the corner rounding of the rib tips and of the flow within the cavities for the four-rib cylinder. Corner rounding is known to increase the critical angle for the square cylinder (Carassale et al, 2014). When comparing the four-rib cylinder results to the square cylinder with the corner rounding closest to the four-rib case (r/b = 1/15.5, where r is the corner radius and b…”

Section: Influence Of the Projected Frontal Widthmentioning

confidence: 99%

Angle of attack dependence of flow past cactus-inspired cylinders with a low number of ribs

Zhdanov

Busse

2019

European Journal of Mechanics - B/Fluids

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The aerodynamic coefficients and the Strouhal number of cylinders with three and four ribs, inspired by succulents Euphorbia trigona and Euphorbia Abyssinica are investigated using 2D Unsteady Reynolds-Averaged Navier-Stokes simulations at Reynolds number 20,000. Both configurations show a significant dependence of the studied characteristics on the angle of attack. The obtained results are compared to the smooth circular cylinder, previous results for cylinders with 24 ribs based on the Saguaro cactus, and cylinders with triangular and square cross-sections. Relative to the circular cylinder, the mean drag coefficient is lowered only for the four-rib case at high angles of attack. However, at some angular positions, the ability to reduce unsteady force fluctuations exceeds Saguaro-inspired cylinders. For both shapes studied, the Strouhal number at most angles of attack is lower compared to both the circular cylinder and cylinders with 24 ribs at the same Reynolds number. The minimum values of the aerodynamic coefficients for both configurations are related to the angular orientation. For the four-rib case a critical angle of α cr ≈ 40 • is observed, at which the mean drag coefficient and the fluctuating lift coefficient attain their minima. The mean lift coefficient reaches at this angle its maximum value before a sudden drop for higher angles of attack. Therefore, for cactus-shaped cylinders with four ribs high angles of attack give the optimum orientation relative to prevailing winds.

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Experimental investigation on the aerodynamic behavior of square cylinders with rounded corners

Cited by 147 publications

References 17 publications

Experimental investigation on the flow over normal flat plates with various corner shapes

Experimental investigation on the flow over normal flat plates with various corner shapes

Effect of Corner Radius in Stabilizing the Low-Re Flow Past a Cylinder

Angle of attack dependence of flow past cactus-inspired cylinders with a low number of ribs

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