Fast flow simulation study of pulsating ventilation performance on air contaminant removal

Fast flow simulation is imperative in the design of pulsating ventilation, which is potentially efficient in indoor air contaminant removal. The execution of the conventional CFD method requires considerable amount of computational resources. In this study, five different numerical schemes were proposed based on fast fluid dynamics (FFD) and fractional step (FS) methods, and were evaluated to achieve quick simulation of airflow/contaminant dispersion. One of these numerical schemes was identified with the best overall computing efficiency for investigating the performance of pulsating ventilation. With this numerical scheme at hand, the air contaminant removal effectiveness of different ventilation types was evaluated. Two kinds of pulsating ventilation and one kind of steady ventilation were tested upon a benchmark isothermal mixing chamber. The effect of adjusting supply velocity parameters on the ventilation performance was also investigated. CO₂ concentration, airflow pattern, and vortex structure of different ventilation types were illustrated and analyzed. The results reveal that the FS method is more suitable for transient simulation of wall-bounded indoor airflow than the FFD method, and 34%–51% of computing time could be saved compared to the conventional CFD method. Regarding the choice of ventilation type, steady ventilation might result in short-circuit airflow and stagnant zones; alternatively, pulsating ventilation has greater potential in air contaminant removal due to its ever-changing vortex structure.