Numerical investigation of inlet opening size on wind-driven cross ventilation

Abstract

The purpose of this study is to investigate the effect of opening size on indoor airflow characteristics of a naturally ventilated building model. The numerical simulation based on 3D-steady RANS equation was performed in this study. A total of five different inlet to outlet opening ratios, namely 1:4, 1:2, 1:1, 2:1 and 9:4 were included in the study and analysed. The results of model validation and grid independence analysis were consistent with the previous study. The simulation results in this study are discussed based on the velocity vector, velocity and pressure, pressure drop and ventilation rate. Through the study, the results have clearly illustrated that the velocity vector, velocity and pressure, pressure drop and ventilation rate are highly dependent on the opening ratio. When air passes through the building model, it forms a recirculation at the top and bottom of the airflow. In addition, the contours of velocity and pressure have indicated that the lower the opening ratio, the higher the velocity and subsequently lower pressure inside the building model. For the pressure drop, the results have shown that the lower the opening ratio, the higher the pressure drop. Beyond that, when the opening ratio is less than 1, the ventilation rate was increased but when the opening ratio greater than 1, the ventilation rate begins to decrease. Therefore, change in the size of inlet opening will greatly affect the performance of ventilation rate.