Flow topology and multi-source contaminant transport in a compounding room under different ventilation strategies

The preparation of antineoplastic drugs in pharmacy intravenous admixture services may generate hazardous particulate contaminants. However, the fluid-dynamic mechanisms governing their transport at the room scale remain difficult to predict. In this study, computational fluid dynamics, Lagrangian particle tracking, and Liutex-based vortex identification were employed to investigate airflow organization, vortex evolution, and particle transport in a hospital compounding room. At 42 ACH, the optimized S-3 configuration used 19.2% less ventilation airflow than the conventional S-6 configuration at 52 ACH. Nevertheless, S-3 achieved a comparable total contaminant removal index at 120 s (99.25% vs 99.17%). Compared with S-6, S-3 increased the proportion of regions with an air age below 60 s by 26.5% and air change efficiency by 48.5%. It also reduced the concentration distribution index by 51.2%. Liutex analysis showed that coherent vortices promoted particle retention and contaminant recirculation near occupied zones. Optimized vent placement weakened these structures and transformed contaminant transport from a recirculation-dominated mode into directional removal. These findings reveal the intrinsic linkage between airflow organization, vortex evolution, and contaminant transport and provide a mechanistic basis for contamination control and ventilation design in healthcare clean environments.