Discussion on grid size and computation domain in CFD simulation of pedestrian wind environment around buildings

With the rapid development of computers and CFD, pedestrian level wind study using CFD has become important in engineering design in recent years. In the United Kingdom, wind study is now a common engineering practice and a mandatory documentation for plan authority. The paper presents preliminary CFD simulation of pedestrian wind environment around buildings of typical configuration, size and orientation. The results were compared for flow pattern and the wind velocity amplification value at the pedestrian level, a horizontal surface 1.5 m above ground.

Optimization of the positions of indoor contaminant sources and sinks by using a new conception-spatial flow influence factor

A new concept, the spatial flow influence factor (SFIF), put forward by us in our previous paper, provides a new insight into the airflow structure. In this paper, several typical illustrative examples are presented to show: (1) how to optimally arrange the chemical pollutant sources and the occupied regions for a given indoor airflow; (2) how to optimize the position of adsorption materials. From the examples,  it is seen that the concept is powerful in the control of indoor air gas pollutants.

Developing computational fluid dynamics conditions for urban natural ventilation study

Computational fluid dynamics (CFD) is a promising method to study the urban built environment. However, the pecularities of the urban wind environment are difficult to simulate with a CFD package. The aim of this work is to develop CFD model capable of simulating the urban boundary layer which can then be used to investigate the effects of built form on the pressure coefficient regeme. The model concentrates on two aspcepts: the boundary conditions and domain size.

Simulation-based performance assessment of slit-type ventilation system for domestic buildings in Korea

The airtight window system adopted in highrise residential buildings or residential-commercial complexes recently in Korea gives rise to poor ventilation, deterioration of Indoor Air Quality (IAQ) and the overloading of cooling systems during the summer season. To address these problems, a slittype ventilation system has been developed. This study is to investigate the performance of the slit-type ventilation system using computer simulation. A thermal model coupled with an air flow network model which represents an apartment with an underfloor heating system was created.

Response of contaminant detection sensors and sensor systems in a commercial aircraft cabin

To reduce the potential risk of airborne infectious diseases during an outbreak or to detect a chemical/biological release by a terrorist, it is essential to place appropriate chemical/biological sensors in commercial airliner cabins. This investigation studied sensor responses along the length of a fully occupied twin-aisle cabin with 210 seats by using a validated Computational Fluid Dynamics (CFD) program. The results revealed that seating arrangements can make cross sectional airflow pattern considerably asymmetrical.

Influence analysis of neutral plane on ventilation in workshop

This paper analyzed the influence of neutral plane on natural ventilation in workshop. For several typical heights of neutral plane of a molding workshop, its influence on ventilation was simulated by means of CFD. In designing natural ventilation, to coordinate the dimensions between the inlet and outlet openings and to play down the neutral plane properly may be the effective measures to increase ventilation efficiency.

Utilizing high performance supercomputing facilities for interactive thermal comfort assessment

We outline the current state of the development of a computational steering environment (CSE) for the interactive simulation and local assessment of indoor thermal comfort. The system consists of a parallel CFD kernel, a fast 3D mesh generator and a virtual reality-based visualization component. The numerical method is based on a lattice Boltzmann algorithm with extensions for simulations of turbulent convective flows.

Pressure coefficient simulated by cfd for wind-driven ventilation analysis

Pressure coefficients (CP) are fundamental to calculate ventilation rates in buildings by the airflow network models (AFN). This paper deals with the use of CFD simulation to calculate Cp, and the use of those Cp values as input in building energy simulations (BES). The commercial package CFX was used to calculate CP for a 5-stories isolated building, typically found in social housing complexes in Brazil, The standard k-ε turbulence model was adopted.

A RSM model for the prediction of heat and mass transfer in a ventilated room

A full-scale test room is used to investigate experimentally and numerically the velocity and temperature fields in the case of a mechanical ventilation. Detailed fields are measured for three cases of ventilation air temperature: an isothermal case, a hot case and a cold case. The experimental data are used to test two turbulence models: a first order k-ε turbulence model and a second order RSM turbulence model. The RSM model predicts the temperature and velocity fields better than the k-ε turbulence model.

Buoyancy-driven natural ventilation of a room with large openings

The buoyancy-driven natural ventilation of a room with large lower and higher level openings is investigated by both theoretical analysis and CFD simulation. Pressure-based formulae are developed for the prediction of the height of neutral plane and airflow rate, and three different flow modes are identified according to the position of the neutral level: (I) when the neutral height is at intermediate level of the lower opening; (II) when the neutral height has no intersection with openings; (III) when the neutral height is at the intermediate level of the higher opening.