Evaluation of various turbulence models for the prediction of the airflow and temperature distributions in atria

Ilie

Mathematical Modelling in Civil Engineering

2014

Accurate assessment of air-flow in ventilated spaces is of major importance for achieving healthy and comfortable indoor environment conditions. The CFD (Computational Fluid Dynamics) technique is nowadays one of the most used approaches in order to improve the indoor air quality in ventilated environments. Nevertheless, CFD has still two main challenges: turbulence modeling and experimental validation. As a result, the objective of this study is to evaluate the performance of different turbulence models potentially appropriate for the prediction of indoor airflow. Accordingly, results obtained with 6 turbulence models (standard k-ε model, RNG k-ε model, realizable k-ε model, LRN SST k-ω model, transition SST k-ω model and low Reynolds Stress-ω model) are thoroughly validated based on detailed experimental data. The configuration taken into account in this work corresponds to isothermal and anisothermal airflows produced by mixing ventilation systems in small enclosures at low room air changes per hour. In general, the transition SST k-ω model shows the better overall behavior in comparison with measurement values. Consequently, the application of this turbulence model is appropriate for air flows in ventilated spaces, being an interesting option to more sophisticated LES (Large Eddy Simulation) models as it requires less computational resources.

Section: Realizable K-ε Two-equation Modelmentioning

confidence: 99%

Appropriate CFD Turbulence Model for Improving Indoor Air Quality of Ventilated Spaces

Ilie

Mathematical Modelling in Civil Engineering

2014

“…In addition, the dissipation term in the energy equation was neglected due to the low velocities involved. As noted from our previous studies [10][11] for the evaluation of turbulence models and from literature survey, the SST-kw turbulence model along with a radiation model DTRM was considered suitable for present CFD simulations. The resultant steady-state governing equations were solved using the commercial CFD solver FLUENT.…”

Section: B Numerical Solution Proceduresmentioning

confidence: 99%

“…In order to utilize the CFD model from the previous studies [10,11], the simulated room was assumed to be located and oriented 0 degree with Longitude (deg) 46.77 and Latitude 24.64 (deg), facing southward in the region of Riyadh city in Saudi Arabia. The room was fully closed to observe the effect of optical properties of glass coatings on net heat transfer gain within the room.…”

Section: A Test Room Design Configurationmentioning

confidence: 99%

Heat Transfer Simulation for Nano-Coated Glass in Saudi Arabia

2016

IJAMAE

Abstract-The amount of heat flow within building interior is important for understanding and predicting its thermal behaviors. To achieve greater energy efficiency of a building, the performance of window system is required to improve. Glazing materials in windows provide adequate illumination levels in the interior of buildings receiving the visible part of solar radiation. The other part of solar radiation in the infrared region entering through glazing causes increase of interior temperature. Hence glazing is a major component in designing and analyzing problems such as energy demands, assessment of heating and cooling loads and thermal comfort in a building. This study focuses on the thermal behavior of glass for development of functional nano-coatings of window glazing for the regional conditions in Saudi-Arabia. Different materials and its optimized film properties of thickness and doping level of antimony tin oxides (ATO) were prepared and their optical and thermal properties were systematically investigated. Glass U-factor, Solar Heat Gain Coefficient (SHGC) and net heat transfer through window were calculated. The results showed that the thermal insulation of the glass effect of coating thickness and doping level was significant. The simulated net heat transfer through window decreased linearly with increase of both of coating thickness or ATO concentration. Furthermore, the overall transmittance in the visible region and reflectance in infrared and ultraviolent regions decrease with increasing of weight content of antimony doped tin oxides ATO, and similarly for increasing of coating thickness.

“…Pimolsiri Prajongsan and Steve Sharples [3] used CFD to analyse the potential of ventilation shafts in multi-storey housing in Bangkok. Shafqat Hussain et al [28][29][30] evaluated various turbulence models for the prediction of the airflow and temperature distributions in atria, which concerns buoyancy-driven natural ventilation. Compared to these previous studies of CFD, there are fewer studies on wind-driven ventilation to evaluate natural ventilation performance in multi-storey housing by the provision of voids in the building.…”

Section: Introductionmentioning

confidence: 99%

The Effects of Void on Natural Ventilation Performance in Multi-Storey Housing

et al. 2016

Abstract:Enhancing natural ventilation performance in multi-storey housing is very important for the living environment in terms of health and thermal comfort purposes. One of the most important design strategies to enhance natural ventilation in multi-storey housing is through the provision of voids. A void is a passive architectural feature, which is located in the middle of deep plan buildings. It is very crucial to consider the configurations of voids in the buildings for enhancing natural ventilation, especially for multi-storey housing. In this study, Malaysian Medium Cost Multi-Storey Housing (MMCMSH), which is an example of multi-storey housing located in a suburban area, has been selected in this study. This study aims to investigate the potential of void for enhancing natural ventilation performance in multi-storey housing by the comparison of two different void configurations. Field measurement of MMCMSH has been conducted to validate Computational Fluid Dynamic (CFD) model and Atmospheric Boundary Layer (ABL) is an important parameter for setting up the CFD Model's domain. Ventilation rate (Q), which is necessary for comfort and health reasons, is an important parameter for the comparison of the different void configurations. This study revealed that the provision of void can enhance natural ventilation performance in multi-storey housing with an increase in the value of Q, from 3.44% to 40.07%, by enlarging the void's width by 50% compared to the existing void.