Numerical study of cross-ventilation using two-equation RANS turbulence models

Cross-ventilation is a mechanism using the pressure difference between the outdoor environment and indoor space to provide an energy-saving method for ventilation design. Since the ventilating flow in the vicinity of the opening is highly turbulent and unsteady, the ideal numerical method to resolve the structure of the ventilating flow is by using a time-dependent approach such as large eddy simulation (LES). However, LES requires large computing resources and there are also some uncertainties associated with the discretisation of time scales and length scales of turbulence. Therefore, an alternative has been sought. This study compared the flow simulations computed by the standard k-ε, RNG k-ε, standard k-ω and SST k-ω models as well as LES and all the results were compared with experimental measurement data. The main findings concluded that the SST k- ω model was able to depict the flow features satisfactorily and that the calculation of flow rate was also accurate under various wind directions.