Flow around three-dimensional obstacles in boundary layers

Becker, Stefan; Lienhart, H.; Durst, F.

doi:10.1016/s0167-6105(01)00209-4

Cited by 85 publications

(52 citation statements)

References 5 publications

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“…16b, and is in agreement with Becker et al (2002). In their study, they consider a single block and then vary the angle of the incoming flow.…”

Section: Vorticity Magnitudesupporting

confidence: 68%

“…In the current study, the reduction in size of one leg appears to take place even for a much smaller angle than the angles considered by Becker et al (2002). However, the shift in location of the legs observed by Becker et al (2002) is not evident for the present study, and may be due to the presence of other blocks in our array or the much smaller incidence angle. Various other methods of structure identification are also investigated and are presented below.…”

Section: Vorticity Magnitudecontrasting

confidence: 64%

“…Even with recent progress in computing, numerical simulations need validation through experimental studies for such complex flow fields. Becker et al (2002) with laser Doppler anemometry (LDA) and Sousa (2002) with 2D-three component particle image velocimetry (2D-3C PIV) measurements were among the first to have looked at three-dimensional flow fields around a single cuboid obstacle. Becker et al (2002) described the effect of the angle of attack, the aspect ratio, the Reynolds number and the boundary-layer type on the flow structures around a single obstacle.…”

mentioning

confidence: 99%

“…Becker et al (2002) with laser Doppler anemometry (LDA) and Sousa (2002) with 2D-three component particle image velocimetry (2D-3C PIV) measurements were among the first to have looked at three-dimensional flow fields around a single cuboid obstacle. Becker et al (2002) described the effect of the angle of attack, the aspect ratio, the Reynolds number and the boundary-layer type on the flow structures around a single obstacle. They found no fundamental changes in the vortex structure for the various boundary layers investigated, and determined that an increase in the power-law coefficient, in…”

mentioning

confidence: 99%

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Stereoscopic Particle Image Velocimetry Measurements in an Urban-Type Boundary Layer: Insight into Flow Regimes and Incidence Angle Effect

Monnier¹,

Neiswander²,

Wark³

2010

Boundary-Layer Meteorol

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An experimental investigation of the three-dimensional flow through an urban-type array (four rows of three cuboid Plexiglas blocks) in a laboratory modelled neutrally stratified atmospheric boundary layer is presented. We concentrate on the effect of the streamwise spacing between adjacent rows defining two different flow regimes (wake interference and skimming flow) as well as the effect of the incident angle of the approaching boundary layer. Stereoscopic particle image velocimetry measurements provide all three components of the velocity field in closely spaced two-dimensional planes in a region located in the middle row downstream of the centre block. It is found that the maximal exchange rate between the fluid within the street and the flow above is for the wake interference regime. Two regions are apparent: one influenced by streamwise velocity fluctuations, the other by spanwise fluctuations. In addition, the incidence angle of the incoming flow has a much more dramatic effect for the wake interference regime that would greatly favour dispersion. Coherent-structure identification tools are applied to obtain information on the shape, extent and localisation of vortical structures.

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“…16b, and is in agreement with Becker et al (2002). In their study, they consider a single block and then vary the angle of the incoming flow.…”

Section: Vorticity Magnitudesupporting

confidence: 68%

Section: Vorticity Magnitudecontrasting

confidence: 64%

mentioning

confidence: 99%

mentioning

confidence: 99%

See 2 more Smart Citations

Stereoscopic Particle Image Velocimetry Measurements in an Urban-Type Boundary Layer: Insight into Flow Regimes and Incidence Angle Effect

Monnier¹,

Neiswander²,

Wark³

2010

Boundary-Layer Meteorol

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“…For example, it was used to study flow around three-dimensional obstacles in boundary layers [3] and in the study of airflow characteristics inside and outside a cross-ventilation model [24]. In the present study spectral energy densities suggest that without screens, inflow is characterized by a lower spectral decay rate than outflow.…”

Section: Discussion and Summarymentioning

confidence: 58%

Heat Fluxes and Airflow Patterns Through Roof Windows in a Naturally Ventilated Enclosure

Teitel

Tanny

2005

Flow Turbulence Combust

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Experiments were carried out to study the airflow and heat transfer through continuous vertical roof openings of a naturally ventilated greenhouse. The major goals of this work were to investigate the effect of ambient wind speed and direction with respect to the greenhouse on the mean and turbulent characteristics of the air velocity and heat transfer through openings with and without insect-proof screens. Air velocity and temperature were measured simultaneously at two edges of the opening using one-dimensional sonic anemometers and miniature thermocouples. It is shown that when the wind is not perpendicular to the plane of the openings there are outflow and inflow, at the windward and leeward edges of the openings respectively. A wind blowing from the back of the openings and nearly perpendicular to them reduced the mean air velocity at the two edges but did not change the turbulent velocity much. Over a considerable part of the day the mean and turbulent air velocities scale with the ambient wind; the total heat flux (mean plus turbulent) scales with the product of the ambient wind and temperature while the turbulent heat flux does not. The integral length scale of the inflow was approximately equal to the height of the opening and was larger than that of the outflow. Installing screens on the openings generated smaller scales and increased the spectral decay rate in comparison with openings without screens. A quadrant analysis enabled the determination of the events that significantly contribute to the turbulent heat flux. It is shown that at the outflow the turbulent heat flux is mainly due to eddies of cool air entering from the surrounding to the greenhouse while at the inflow it is due to both warm and cool eddies leaving and entering the greenhouse respectively. Nomenclature C p = specific heat of air, J kg −1 K −1 Co = co-spectra of velocity and temperature fluctuations, m s −1 K E = spectral density function, m 3 s −2 f = frequency, Hz F u = velocity flatness F θ = temperature flatness H = threshold H c = total heat flux, W m −2 L = integral length scale, m r uθ = correlation coefficient between u and θ 22 M. TEITEL AND J. TANNY R (t) = autocorrelation function of velocity S i,H = normalized conditional heat flux S u = velocity skewness S θ = temperature skewness T = temperature, K T 0 = ambient temperature, K u = fluctuating air velocity through the opening, m s −1 u = RMS of velocity, m s −1 U = mean air velocity through the opening, m s −1 U 0 = ambient wind speed, m s −1 U n = normalized mean air velocity through the opening u n = normalized RMS of velocityGreek Symbols θ = temperature fluctuation, K θ = RMS of temperature, K ρ = air density, Kg m −3 T = temperature difference between air at the opening and the ambient, K T a = temperature difference between average greenhouse air and the ambient, K

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Computational Fluid Dynamics Applied in High‐Pressure Processing Scale‐Up

Rauh

Delgado

2011

Innovative Food Processing Technologies: Advances in Multiphysics Simulation

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Flow around three-dimensional obstacles in boundary layers

Cited by 85 publications

References 5 publications

Stereoscopic Particle Image Velocimetry Measurements in an Urban-Type Boundary Layer: Insight into Flow Regimes and Incidence Angle Effect

Stereoscopic Particle Image Velocimetry Measurements in an Urban-Type Boundary Layer: Insight into Flow Regimes and Incidence Angle Effect

Heat Fluxes and Airflow Patterns Through Roof Windows in a Naturally Ventilated Enclosure

Computational Fluid Dynamics Applied in High‐Pressure Processing Scale‐Up

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