Development of a model for single-sided, wind-driven natural ventilation in buildings

Abstract

Natural ventilation is a simple and energy-efficient method to adjust the indoor environment. This study aims to develop a model for predicting the total flow rate of single-sided natural ventilation. It is motivated by the fact that the wind-driven ventilation itself is commonly considered to consist two components – a mean component and a fluctuating component. Pulsating flow rate, mean and broadband ventilation rate are discussed and considered in the model due to fluctuating wind velocity driven by the fluctuating pressures and unsteady flows around the opening. The new model shows that the total flow rate is majorly caused by pulsating flow when the area of opening is small, but it is mainly caused by mean flow in the case of large opening. Opening ratio can be taken as a boundary to distinguish the small opening area and the larger one from the case analyses in this study. Reynolds Averaged Navier-Stoke model, large eddy simulation, and other correlations are utilized to validate the developed model. The results of current method agree reasonably well with those of transient simulation. Finally, a simplified version of the model is developed which is useful for predicting the total flow rate of natural ventilation in buildings. Practical application: The model can be applied to predict the total flow rate of single-sided natural ventilation in buildings due to wind pressure. The model shows that the total flow rate is majorly caused by the pulsating flow when the area of opening is small, but it is mainly caused by the mean flow in the case of large opening. An opening ratio of 3% can be taken as a boundary to distinguish the small opening area and the large one from the cases analysed in this study.