Impact of roof geometry of an isolated leeward sawtooth roof building on cross-ventilation: Straight, concave, hybrid or convex?

Perén, J.I.; Hooff, T. van; Ramponi, R Rubina; Blocken, Bje Bert; Leite, Brenda Chaves Coelho

doi:10.1016/j.jweia.2015.05.014

Cited by 52 publications

(34 citation statements)

References 30 publications

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“…Li et al, 2000;Hensen, 2004;Hirano et al, 2006;Hensen and Lamberts, 2011) and Computational Fluid Dynamics (CFD) models (e.g. Kato et al, 1992;Kato et al, 1997;Reichrath and Davies, 2002;Jiang et al, 2003;Heiselberg et al, 2004;Evola and Popov, 2006;Norton et al, 2007;Meroney, 2009;Blocken, 2010a, 2010b;Ramponi and Blocken, 2012a;Peren et al, 2015).…”

Section: Introductionmentioning

confidence: 99%

Wind tunnel analysis of flow and dispersion in cross-ventilated isolated buildings: Impact of opening positions

Tominaga

Blocken

2016

Journal of Wind Engineering and Industrial Aerodynamics

107

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a b s t r a c tThis paper presents a detailed experimental analysis of flow and dispersion by cross-ventilation in five generic isolated single-zone buildings with different opening positions. First, flow visualization is performed illustrating the highly transient flow and dispersion process dominated by a flapping jet with pronounced Kelvin-Helmholtz instabilities. Next, the mean velocity field, the turbulent kinetic energy field, the mean concentration field and the concentration fluctuation field are presented and analyzed. Finally, time histories of the instantaneous concentration in the building are provided. The contaminant dispersion in the cross-ventilated flow is strongly influenced by the overall flow pattern that is largely determined by the inlet opening position, while the outlet opening position seems less important. The results provide new insights in the flow and dispersion process inside cross-ventilated buildings and can be used to validate Computational Fluid Dynamics (CFD) simulations of flow and dispersion by crossventilation and for the subsequent establishment of new CFD best practice guidelines. It is also shown that the use of different ventilation performance parameters yields a different ranking of the configurations in terms of ventilation performance. Care should therefore be applied when evaluating ventilation performance based on only flow rates or velocities as opposed to dispersion quantities.

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Section: Introductionmentioning

confidence: 99%

Wind tunnel analysis of flow and dispersion in cross-ventilated isolated buildings: Impact of opening positions

Tominaga

Blocken

2016

Journal of Wind Engineering and Industrial Aerodynamics

107

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“…4 shows the dimensions of the computational domain, a perspective view of the grid on the building and ground surface and perspective views of the grid on the building surfaces (front and back view) for the reference case building (Geometry A). The grid resolution is based on the gridsensitivity analysis presented in Per en et al [17]. The total number of cells is 1,961,524 cells for the reference case, and it varies for each configuration due to the inclusion of the windward and/or leeward eaves, ranging from 1.9 to 2.4 million cells.…”

Section: Computational Geometry Domain and Gridmentioning

confidence: 99%

“…This holds particularly for leeward sawtooth roof buildings. In previous studies by the authors [16,17], the impact of the roof inclination angle [16] and the roof shape [17] on cross-ventilation of leeward sawtooth roof buildings were assessed. The present study builds further on these achievements by reporting a detailed and systematic study on the impact of both windward and leeward eaves on wind-driven upward cross-ventilation of a leeward sawtooth roof building.…”

Section: Introductionmentioning

confidence: 99%

“…1c, d). Leeward sawtooth roof geometry A has a straight upward sloping roof and is selected for this sensitivity analysis as a reference case since it reached the highest volume flow rate compared to other leeward sawtooth roof geometries in a previously published paper by the authors [17]. The building dimensions are 3 Â 6 Â 5.7 m 3 (W Â L Â H).…”

Section: Introductionmentioning

confidence: 99%

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Impact of eaves on cross-ventilation of a generic isolated leeward sawtooth roof building: Windward eaves, leeward eaves and eaves inclination

Perén

Hooff

Leite

et al. 2015

Building and Environment

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a b s t r a c tAn eaves is a roof extension that can protect the indoor environment from direct solar radiation, the exterior facade from wetting of by wind-driven rain and can be useful to enhance cross-ventilation. This paper evaluates the impact of eaves configuration on wind-driven cross-ventilation of a generic leeward sawtooth roof building. Both the type of eaves (windward versus leeward) and the eaves inclination angles are investigated. Isothermal Computational Fluid Dynamics (CFD) simulations are performed using the 3D steady Reynolds-Averaged NaviereStokes (RANS) approach. A grid-sensitivity analysis is performed and validation of the CFD results is conducted based on wind-tunnel measurements with Particle Image Velocimetry from literature. The ventilation evaluation is based on the volume flow rates and the indoor mean velocities. The eaves length is 1/4 of the building depth and the inclination is varied between 90 and À45 for both the windward and leeward eaves. The results show that windward eaves with an inclination of 27 (equal to roof inclination) result in the highest increase of the volume flow rate (15%) compared to the building without eaves. Furthermore, the flow through the occupied zone is more horizontally directed. Leeward eaves have a smaller influence on the ventilation volume flow rate than windward eaves; the maximum increase in volume flow rate is only 6% when a 90 inclination is employed. Application of both (windward and leeward eaves) results in an increase of the volume flow rate of 24%, which is 3% more than the sum of the increases by the two eaves separately.

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“…Many researchers have utilized the aerodynamic potential of building façades to investigate their enhancement effect on indoor and outdoor airflow exchanges for both cross and single-sided ventilation buildings [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21]. Typical building façades include a venturi-shaped roof [13], wind catchers [9,[14][15][16], a ventilation shaft [17], wing walls [8], a balcony [7,10,11,18], and eaves [5,6,21].…”

Section: Introductionmentioning

confidence: 99%

Enhanced Single-Sided Ventilation with Overhang in Buildings

2016

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Abstract:Enhancing the ventilation performance of energy-efficient buildings with single-sided openings is important because their ventilation performance is poor and strongly depends on the wind conditions. We considered an overhang as a potential building façade for improving the single-sided ventilation performance. We performed numerical simulations of three-dimensional unsteady turbulent flows over an idealized building with an overhang in order to investigate the effect of the overhang on the ventilation performance. Parametric studies were systematically carried out where the overhang length, wind speed, and wind direction were varied. The numerical results showed that the overhang drastically enhanced the ventilation rate in the windward direction regardless of the wind speed. This is because, for windward cases, the overhang produces a vortex with strong flow separation near the tip of the overhang, which promotes a net airflow exchange at the entrance and increases the ventilation rate. However, the ventilation rates for the leeward and side cases are slightly decreased with the overhang. Using an overhang with single-sided ventilation greatly reduces the local mean age of air (LMA) in the windward direction but increases it in the leeward direction.

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Impact of roof geometry of an isolated leeward sawtooth roof building on cross-ventilation: Straight, concave, hybrid or convex?

Cited by 52 publications

References 30 publications

Wind tunnel analysis of flow and dispersion in cross-ventilated isolated buildings: Impact of opening positions

Wind tunnel analysis of flow and dispersion in cross-ventilated isolated buildings: Impact of opening positions

Impact of eaves on cross-ventilation of a generic isolated leeward sawtooth roof building: Windward eaves, leeward eaves and eaves inclination

Enhanced Single-Sided Ventilation with Overhang in Buildings

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