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computational fluid dynamics

Solar-Wind Generated Roof Ventilation System (SiVATAS) for a Warm-Humid Climate

This research grows out of a desire to find a Solar-Wind Generated Roof Ventilation System for low-cost dwellings located in high building density urban areas where horizontal air movement is restricted. A general purpose computational fluid dynamics (CFD-ACE+) program was utilised to explore, analyse and develop a roof model based on its aerodynamics and thermal performance to obtain optimum wind pressure and temperature differences. Comparisons were made with physical scale models.

A CFD Analysis of the Air Flow Characteristics at an Inflow Opening

In the present study, a numerical simulation to simulate an experiment for evaluating the cross-ventilation performance at an inflow opening by using Large Eddy Simulation (LES), the standard k-e model, and Durbin's k-e model was performed. Results showed that too much turbulent kinetic energy was produced at the leeward opening frame in the standard k-e model. However , Durbin's k-e model improved this defect , and reproduced the wind tunnel results fairly well, as did the LES approach.

A Wind Tunnel Full-Scale Building Model Comparison between Experimental and CFD Results based on the Standard k-e Turbulence Representation

To evaluate the property of cross ventilation quantitatively, it is important that the calculated air flow field is compared with measurement. In this paper, the air flow field in the wind tunnel of the Building Research Institute of Japan (BRI) was calculated by CFD analysis using the standard k- e model, and the adequacy of the calculation was examined by comparison with measured values.

An Alternative View on the Theory of Cross-Ventilation

The mechanism of cross ventilation is dealt with in this paper. The results are obtained by a combination of wind tunnel studies and CFD predictions using a Reynolds stress model as the turbulence model. All buildings have been exposed to a uniform velocity field and therefore the reference flow rate for an opening is equal to the velocity multiplied by the opening area. The openings were located at or close to the position of the stagnation point on the corresponding sealed building.

Application of CFD to Predict and Control Chemical and Biological Agent Dispersion in Buildings

Terrorist attack in buildings by chemical and biological agents (CBAs) is a reality in our lives. This study applies computational fluid dynamics (CFD) to predict CBA dispersion in an office building in order to find the best locations for CBA sensors and to develop effective ventilation systems to protect building occupants in case of indoor CBA releases. It is found that the CFD is a useful tool for such an application, while some challenges remain.

NUMERICAL ANALYSIS OF INDOOR AIR FLOW IN A ROOM VENTILATED BY A HORIZONTAL JET

The goal of this work is to investigate the ability of three eddy viscosity turbulent models, the standardk-?, the RNG k-? and the k-?, in predicting the three-dimensional airflow in a room under forcedconvection. The experimental data from Nielsen (1990), which represents a large room where the airenters horizontally at the top of one side and leaves the room at the bottom of the opposite side, wasused to validate the models. The mean velocity and the turbulence intensity profiles for Reynoldsnumber of 5,000 are presented in two planes of the room with two inlet arrangements.

COMPUTATIONAL FLUID DYNAMICS FOR INDOOR ENVIRONMENT MODELING: PAST, PRESENT, AND FUTURE

This paper gave an overview of the past and present applications of various Computational FluidDynamics (CFD) methods for indoor environment modeling. Typical applications used the CFD tocalculate airflow, air temperature, contaminant concentrations, and turbulence in enclosed environmentfor studying or designing thermal comfort and indoor air quality. With simple airflow and geometry, theCFD is capable of calculating accurately mean flow parameters but less accurately turbulenceparameters.

Flow Patterns Effects on Night Cooling Ventilation

The passive cooling techniques such as night time cross ventilation is potentially an interesting strategy to provide substantial cooling energy savings in warm climates. The efficiency of the night cooling ventilation is determined by three main factors: the external air flow rate in the room, the flow pattern and the thermal mass distribution. Most of the software used to simulate building thermal performance assumes natural convection in the enclosure; therefore the convective heat transfer coefficients for internal room surfaces are underestimated.

Effectiveness of Purging in an Air-Conditioned Office Building in Singapore

This paper investigates the effectiveness of a Purging System in a high-rise office building in Singapore with the aim of improving indoor air quality. The study initially adopts a continuous monitoring concept to investigate the impact of a daily purging operation on pollutant concentration levels at the low, middle and high floors of the office building. Pollutants investigated include formaldehyde, carbon dioxide, carbon monoxide and total volatile organic compounds (TVOC).

Effect of internal partitioning on indoor air quality of rooms with mixing ventilation - basic study -

This paper sums up the results of a study on the internal partitioning with its effects on the room air quality along with the ventilation performance. Physical tests and numerical modeling for a CFD simulation were used to evaluate different test conditions that employed mixing ventilation from the ceiling.

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