English

This paper is a presentation of a detailed mathematical simulation along with an experimental investigation of airflow in solar chimneys carried out with an experimental apparatus whose most of the variables could be changed during the experiments. It is a chimney channel with changeable channel thickness and inclination angle.
The simulation model used proved very useful to simulate solar chimneys performance. It can predict flow rates for a wide range of variables.

LES (Large Eddy Simulation) has bben used to simulate cross ventilation under various wind direction angles. A new model, named local similarity model of cross ventilation, is proposed to estimate cross-ventilation flow rate and inflow angle at opening. In order to validate the proposed model, a wind tunnel experiment using a building model was carried out. The results confirm that dynamic similarity is established almost regardless of wind direction angle and position of the opening.

The study of buoyancy-driven natural ventilation in buildings requires windless conditions. It is difficult to conduct on-site measurements since the nature has few windless moments so a full-scale test room placed in a large laboratory environment can create artificially such conditions but it is an expensive method. CFD methods using two different models (RANS and LES) provide an alternative approach to study natural ventilation in buildings.

Due to the renewal of interest for solar chimneys (that convert thermal energy into the kinetic energy of air movement) , experiments were carried out in a controlled environment, with a full-scale chimney, where both air-velocity and air-temperature were measured.
The aim of the project was to get a better knowledge of :
- optimal gap to height ratio
- optimal gap to different heat input ratio
- optimal inclination angle
- methods to estimate the flow rate.

This paper sums up the developments in geophysical fluid dynamics and ocean currents related to dynamical phenomena. Examples from study of ocean flows are given, then several methods for studying nonlinear dynamical phenomena proposed. Those dynamical phenomena can be very significant for smoke control in naturally and hybrid ventilated buildings.

In this paper, after theoretical considerations, two ventilation openings are analysed : an opening with top-hinged flap and a wall inlet with central flap. The analysis shows that it is possible to split artificial resistance coefficients from literature into pure resistance and pure contraction coefficients .

This paper develops a simple analytical model for the air flow inside a room with different discrete heating and cooling sources, established by combined localised and distributed heat input. Results from experiments are compared to simple theoretical models of the flow pattern.

In this paper, cross ventilation is evaluated by the multi zone network airflow simulation and using CFD. The distribution of indoor wind velocity by cross ventilation is influenced by the weather condition, the location of the building and the form of he building. This paper takes into account those three indexes and proposes a new evaluation method of natural cross ventilation performance

The wind tunnel experiment is the major method for cross ventilation researches. Up to now no quantitative evaluation method nor standard has been produced. This research project is to develop the quantitative method to predict cross ventilation rate driven by wind. A specially designed wind tunnel is used in the project. Conventional wind tunnel experiment is carried out in parallel with scale models of building without openings.

CFD and fluid net models used for natural ventilation designs do not consider the impacts of fluctuating characteristics to the mean airflow rate. This paper presents first a correctional method for predicting mean airflow rate of natural ventilation when the average wind velocity is more important than velocity fluctuation. A correctional coefficient for airflow resistance of multi-zone models is deduced. This method is then applied to a big atrium of a naturally ventilated five floor laboratory.