Mechanism of drag reduction for circular cylinders with patterned surface

Butt, Usman; Jehring, L.; Egbers, Christoph

doi:10.1016/j.ijheatfluidflow.2013.10.008

Cited by 30 publications

(12 citation statements)

References 13 publications

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“…The following ideas have been previously tested: grooves, [3][4][5] bumps and dimples, [6][7][8] and screens, [9,10] among others. These studies showed that surface manipulation can effectively delay the separation point.…”

Section: Discussionmentioning

confidence: 99%

“…[2] The current paper will deal strictly with passive mechanisms.The majority of techniques researched with cylindrical structures involves surface manipulation, such as added roughness or patterns. The following ideas have been previously tested: grooves, [3][4][5] bumps and dimples, [6][7][8] and screens, [9,10] among others. These studies showed that surface manipulation can effectively delay the separation point.…”

mentioning

confidence: 99%

“…For example, the drag coefficient in a study was reduced by 34.2% at a Reynolds number of 2 × 10 5 after incorporating bumps onto the previously smooth cylinder. [7] Another experiment showed U-grooves were able to reduce the drag coefficient by 18.6% at a Reynolds number of 1.4 × 10 5 . [4] All surface manipulation techniques reviewed so far were conducted under the uniform, non-ABL (atmospheric boundary layer) condition.…”

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confidence: 99%

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Surface pressure distribution on patterned cylinders under simulated atmospheric boundary layer winds

Ferreira

Amirinia

Jung

2017

Structural Design Tall Build

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SummaryExtensive research has been previously conducted on pressure distribution of cylindrical models under uniform and laminar flow conditions. However, typical civil structures such as high-rise buildings or towers are under the atmospheric boundary layer (ABL) conditions. Knowing this, the present research aims to quantify the effectiveness of surface patterns in reducing the suction zone under a simulated ABL condition. Two different surface patterns, U-grooved and V-grooved, were selected to be tested in wind tunnel. In addition to patterned cylinders, tests were also conducted on a smooth-surfaced cylinder, serving as the control of the experiment. An array of roughness elements was placed at the upstream end of the test section with the purpose of inducing ABL winds within the test section. Without the ABL wind, the cylinder covered in V-grooved riblets was most effective in reducing the suction zone followed by the U-grooved cylinder. With the simulated ABL condition, V-grooved cylinder continued to show decreased suction although the amount of decrease was less. Both grooved cylinders showed decreased peak pressure coefficients under the ABL condition compared to the non-ABL condition.KEYWORDS atmospheric boundary layer, cylinder, flow separation, pressure coefficient, surface pattern, wind tunnel 1 | INTRODUCTION High-rise buildings, categorized as any structure requiring the use of a mechanical vertical transportation system (i.e., elevators), can vary greatly in size, from a common 10-story office building to the 828-m-tall Burj Khalifa in Dubai. Although each structure faces its own design challenges, wind is a major determining factor in high-rise buildings.As wind strikes a structure, flow may remain attached or be separated from the surface of the structure. The windward side experiences a positive pressure whereas the leeward side experiences a negative pressure, often referred to as suction. [1] Flow separation typically causes an increase in pressure drag that is the form of drag caused by the pressure differences between the front (windward) and rear (leeward) surface of a structure. By delaying the separation point (occurring at a leeward point), pressure drag can be reduced.All experiments related to delaying the flow separation can be grouped into 2 major categories, passive or active. A passive mechanism is one that is related to the building architecture, where features are intentionally incorporated into a design in order to dictate fluid flow around a particular surface. Oppositely, an active mechanism requires that external energy be added into a particular system. [2] The current paper will deal strictly with passive mechanisms.The majority of techniques researched with cylindrical structures involves surface manipulation, such as added roughness or patterns. The following ideas have been previously tested: grooves, [3][4][5] bumps and dimples, [6][7][8] and screens, [9,10] among others. These studies showed that surface manipulation can effectively delay the separation point. Delay...

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Section: Discussionmentioning

confidence: 99%

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confidence: 99%

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Surface pressure distribution on patterned cylinders under simulated atmospheric boundary layer winds

Ferreira

Amirinia

Jung

2017

Structural Design Tall Build

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“…Butt et al [5] investigated the flow over cylinders with hexagonal dimples (k/D = 1.98 Â 10 À2 ) in a subsonic wind tunnel over the range Re = 3.14 Â 10 4 -2.77 Â 10 5 . Their results showed that the dimpled cylinder could achieve a drag coefficient of about 0.65 times of a smooth one.…”

Section: Introductionmentioning

confidence: 99%

Control of flow past a dimpled circular cylinder

Zhou

Wang

Guo

et al. 2015

Experimental Thermal and Fluid Science

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“…Williamson and Govardhan (2004) summarized the state of the arts on vortex formation in the wake of stationary and oscillating cylinders. There has been a lot research effort dedicated to reduce the drag force on the cylinder, mainly using passive wake/vortex control methods either by changing the surface texture or by attaching protruding (Guven et al, 1980;Lo and Ko, 1999;Huang, 2011) and other setups (Tsutsui and Igarashi, 2002;Hwang and Yang, 2007;Butt et al, 2014).…”

Section: Introductionmentioning

confidence: 99%