Stream Tube based Analysis of Problems in Prediction of Cross-Ventilation Rate

Kobayashi, Tomohiro; Sagara, Kazunobu; Yamanaka, Tatsuhiko; Kotani, Hisashi; Takeda, Shogo; Sandberg, Mats

doi:10.1080/14733315.2009.11683822

Cited by 21 publications

(16 citation statements)

References 7 publications

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“…14b, which shows that the RSM and the standard k-ω models tend to overpredict the experimental values by up to 9 times (x/D = 0.6). Note that in several previous studies, authors pointed out the superior performance of the RNG k-ε model for indoor air flow modeling, especially compared to the standard k-ε model [41,50,64,71]. This is to a large degree confirmed by our study.…”

Section: Impact Of Turbulence Modelsupporting

confidence: 79%

“…It assumes that the turbulent kinetic energy is dissipated at the windward opening and that the effect of the dynamic pressure on the air flow passing through the opening is negligible [20,25,28,39,73,92]. However, Murakami et al [20], Kato et al [21], Sandberg [93], Karava et al [16,28], Kobayashi et al [71,73] correctly pointed out that in case of wind flow through large ventilation openings, the turbulent kinetic energy is rather preserved and the sealed-body assumption is therefore not longer valid. A virtual stream-tube model was introduced to explain the direct connection between the inlet and outlet openings [20,21,71,73,93].…”

Section: Introductionmentioning

confidence: 99%

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CFD simulation of cross-ventilation for a generic isolated building: Impact of computational parameters

Ramponi

Blocken

2012

Building and Environment

456

271

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• Extensive literature review on numerical cross-ventilation studies in overview table.• Detailed sensitivity analysis for CFD simulations of a cross-ventilated building model.• The SST k-ω turbulence model shows the best agreement with PIV measurements.• The turbulent kinetic energy strongly influences the convergence and the results.• The prediction of the outdoor standing vortex largely affects the indoor airflow. AbstractAccurate CFD simulation of coupled outdoor wind flow and indoor air flow is essential for the design and evaluation of natural cross-ventilation strategies for buildings. It is widely recognized that CFD simulations can be very sensitive to the large number of computational parameters that have to be set by the user. Therefore, detailed and generic sensitivity analyses of the impact of these parameters on the simulation results are important to provide guidance for the execution and evaluation of future CFD studies. A detailed review of the literature indicates that there is a lack of extensive generic sensitivity studies for CFD simulation of natural cross-ventilation. In order to provide such a study, this paper presents a series of coupled 3D steady RANS simulations for a generic isolated building. The CFD simulations are validated based on detailed wind tunnel experiments with Particle Image Velocimetry. The impact of a wide range of computational parameters is investigated, including the size of the computational domain, the resolution of the computational grid, the inlet turbulent kinetic energy profile of the atmospheric boundary layer, the turbulence model, the order of the discretization schemes and the iterative convergence criteria. Specific attention is given to the problem of oscillatory convergence that was observed during some of these coupled CFD simulations. Based on this analysis, the paper identifies the most important parameters. The intention is to contribute to improved accuracy, reliability and evaluation of coupled CFD simulations for cross-ventilation assessment.

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Section: Impact Of Turbulence Modelsupporting

confidence: 79%

Section: Introductionmentioning

confidence: 99%

CFD simulation of cross-ventilation for a generic isolated building: Impact of computational parameters

Ramponi

Blocken

2012

Building and Environment

456

271

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“…The decoupled approach is simplified compared to the coupled approach, but it is only efficient for certain phenomena. Many studies have verified the applicability of the decoupled approach (Seifert et al 2006;Kobayashi et al 2009Kobayashi et al , 2010. This approach Fig.…”

Section: Decoupled Outdoor Wind and Indoor Infiltrationmentioning

confidence: 92%

Air infiltration induced inter-unit dispersion and infectious risk assessment in a high-rise residential building

Niu

2017

Build. Simul.

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Identifying possible airborne transmission routes and assessing the associated infectious risks are essential for implementing effective control measures. This study focuses on the infiltration-induced inter-unit pollutant dispersion in a high-rise residential (HRR) building. The outdoor wind pressure distribution on the building facades was obtained from the wind tunnel experiments. And the inter-household infiltration and tracer gas transmission were simulated using multi-zone model. The risk levels along building height and under different wind directions were examined, and influence of component leakage area was analysed. It is found that, the cross-infection risk can be over 20% because of the low air infiltration rate below 0.7 ACH, which is significantly higher than the risk of 9% obtained in our previous on-site measurement with air change rate over 3 ACH. As the air infiltration rate increases along building height, cross-infection risk is generally higher on the lower floors. The effect of wind direction on inter-unit dispersion level is significant, and the presence of a contaminant source in the windward side results in the highest cross-infection risks in other adjacent units on the same floor. Properly improving internal components tightness and increasing air change via external components are beneficial to the control of internal inter-unit transmission induced by infiltration. However, this approach may increase the cross-infection via the external transmission, and effective control measures should be further explored considering multiple transmission routes.

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“…The two openings on opposite walls have the same area and the same height above ground. In these conditions, it is possible to make the assumption of an unidirectional flow based on the virtual stream tube phenomenon [39] which has been used and validated by several authors [40][41][42].…”

Section: Site and Building Overviewmentioning

confidence: 99%

Assessment of different airflow modeling approaches on a naturally ventilated Mediterranean building

Faggianelli

Brun

Wurtz

et al. 2015

Energy and Buildings

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Stream Tube based Analysis of Problems in Prediction of Cross-Ventilation Rate

Cited by 21 publications

References 7 publications

CFD simulation of cross-ventilation for a generic isolated building: Impact of computational parameters

CFD simulation of cross-ventilation for a generic isolated building: Impact of computational parameters

Air infiltration induced inter-unit dispersion and infectious risk assessment in a high-rise residential building

Assessment of different airflow modeling approaches on a naturally ventilated Mediterranean building

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