The flow around a surface-mounted cube in uniform and turbulent streams

Castro, Ian P.; Robins, Alan

doi:10.1017/s0022112077000172

Cited by 604 publications

(321 citation statements)

References 10 publications

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“…The profiles in Fig.16(a) negative pressures occur just beyond separation and are followed by a substantial pressure recovery associated with the attachment process on the top surface, as shown frequently in previous studies (e.g. Castro & Robins, 1977). Note that the data are similar to the field data (at Re h = 2.8 × 10 6 ) of Richards et al (2001) which were obtained in similar conditions (e.g.…”

Section: Mean Near-surface Conditionssupporting

confidence: 82%

Flow around a cube in a turbulent boundary layer: LES and experiment

Lim

Thomas

Castro

2009

Journal of Wind Engineering and Industrial Aerodynamics

136

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We present a numerical simulation of flow around a surface mounted cube placed in a turbulent boundary layer which, although representing a typical wind environment, has been specifically tailored to match a series of wind tunnel observations. The simulations were carried out at a Reynolds number, based on the velocity U at the cube height h, of 20, 000 -large enough that many aspects of the flow are effectively Reynolds number independent. The turbulence intensity was about 18% at the cube height, and the integral length scale L u x was about 0.8 times the cube height h. The Jenson number Je = h/z0, based on the approach flow roughness length z0, was 600, to match the wind tunnel situation. The computational mesh was uniform with a spacing of h/32, aiding rapid convergence of the multigrid solver, and the governing equations were discretised using second order finite differences within a parallel multiblock environment. The results presented include detailed comparison between measurements and LES computations of both the inflow boundary layer and the flow field around the cube including mean and fluctuating surface pressures. It is concluded that provided properly formulated inflow and surface boundary conditions are used, LES is now a viable tool for use in wind engineering problems concerning flow over isolated bodies. In particular, both mean and fluctuating surface pressures can be obtained with a similar degree of uncertainty as usually associated with wind tunnel modelling.

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Section: Mean Near-surface Conditionssupporting

confidence: 82%

Flow around a cube in a turbulent boundary layer: LES and experiment

Lim

Thomas

Castro

2009

Journal of Wind Engineering and Industrial Aerodynamics

136

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“…Finally, it should be noted that, in general, the C D of an obstacle impinged by a turbulent ow can increase if turbulence levels are suppressed (Castro and Robins, 1977). Contrary to Nicolle and Eames (2011) and Chang and Constantinescu (2015) the patches investigated herein are impinged by a fully turbulent boundary layer (i.e.…”

Section: Rementioning

confidence: 90%

Characterisation of drag and wake properties of canopy patches immersed in turbulent boundary layers

2016

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The wakes and the drag forces of canopy patches with di erent densities, immersed in turbulent boundary layers, are investigated experimentally. The patches are circular (with outer diameter D) and are made of several identical circular cylinders (height, H and diameter, d). The bulk aspect ratio of all the patches (AR = H D) was xed at 1 and the patch density (φ = Ncd 2 D 2 , also referred to as solidity) is altered by varying the number of cylinders (Nc) in the patch. Drag measurements show that the patch drag coe cient increases with increasing density. However, the drag coe cient of the highest investigated density (φ ≈ 0.25) is greater than the drag coe cient of a solid patch (i.e. φ = 1, which is a solid cylinder with AR = 1). PIV measurements were carried out along streamwise-wall-normal (x − y) plane along the centreline of patch and in the streamwise-spanwise (x − z) plane at its mid height (i.e. y = H 2). Mean velocity elds show that the porosity of the patch promotes bleeding along all directions. It was observed that bleeding along the vertical/horizontal direction increases/decreases with increasing φ. Furthermore, it was also observed that bleeding along the lateral direction dictates the point of ow separation along the sides of the patch and makes it independent of φ. All these aspects make wakes for porous patches markedly di erent from their solid counterpart and provide a rational basis to explain the observed trends in the drag coe cient.

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“…The value of the critical Reynolds number is difficult to determine due to varying conditions but literature generally shows that fully developed turbulent flow is seen in values above 7500 (35)(36)(37)(38)(39)(40)(41).…”

Section: Similarity Analysismentioning

confidence: 99%

A study of passive ventilation integrated with heat recovery

O’Connor

Calautit

Hughes

2014

Energy and Buildings

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To meet the demand for energy demand reduction in heating, ventilation and air-conditioning systems, a novel design incorporating a heat recovery device into a wind tower was proposed. The integrated system uses a rotary thermal wheel for heat recovery at the base of the wind tower. A 1:10 scale prototype of the system was created and tested experimentally in a closed-loop subsonic wind tunnel to validate the Computational Fluid Dynamics (CFD) investigation. Wind towers have been shown to be capable of providing adequate ventilation in line with British Standards and the Chartered Institution of Building Services Engineers (CIBSE) guidelines. Despite the blockage of the rotary thermal wheel, ventilation rates were above recommendations. In a classroom with an occupancy density of 1.8m 2 /person, the wind tower with rotary thermal wheel was experimentally shown to provide 9L/s per person at an inlet air velocity of 3m/s, 1L/s per person higher than recommended ventilation rates. This is possible with a pressure drop across the heat exchanger of 4.33Pa. In addition to sufficient ventilation, the heat in the exhaust airstreams was captured and transferred to the incoming airstream, raising the temperature 2°C, this passive recovery has the potential to reduce demand on space heating systems.

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The flow around a surface-mounted cube in uniform and turbulent streams

Cited by 604 publications

References 10 publications

Flow around a cube in a turbulent boundary layer: LES and experiment

Flow around a cube in a turbulent boundary layer: LES and experiment

Characterisation of drag and wake properties of canopy patches immersed in turbulent boundary layers

A study of passive ventilation integrated with heat recovery

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