Computational fluid dynamics for cross-ventilated airflow in an urban building

In this study, the velocity field in a naturally ventilated building within an urban-like array was explored using large-eddy simulations. Reduced-scale building models were used to examine the impacts of the geometric conditions in the surrounding buildings and cross-ventilating windows on the flow statistics and instantaneous velocity fields in the sheltered building. The instantaneous velocity components averaged in the opening area were calculated for each condition of the building arrays and openings. The results indicate that the surrounding urban geometry significantly affects the turbulent opening velocities. Additionally, the three-dimensional instantaneous velocity distributions within the target building clearly demonstrate considerable differences under the different building and opening conditions. Such differences also affect the mean, maximum, and minimum wind speeds within the indoor regions. Moreover, the distributions of the two-point correlation coefficient (defined by the velocities normal to the windows at the center of the windward opening and inside the building) were compared for each condition. The strong correlations near the two openings indicate that the instantaneous velocity generated by the surrounding buildings is an important factor in determining the statistical and instantaneous features of indoor ventilating airflows.