There has been an increase in diseases caused by airborne infections such as influenza A/H1N1 or SARS in the recent years. Airborne infection isolation rooms are commonly used to limit the spread of airborne infections. The challenge today is that there is only a limited number of airborne infection isolation rooms in each hospital (class P4). The rooms are expensive to build and airflow control to avoid contamination is often complicated. Pressure difference between the isolation rooms and the corridor ensures that persons who stay outside the isolation are protected against the infected person. An ongoing research project aims to achieve a 90% reduction of transferred particles using 10% of the cost compared to the strictest class of airborne infection isolation rooms.
As part of this project CFD (Computational Fluid Dynamics) simulations have been performed for the “baseline cases”, i.e. air flows induced by opening and closing a hinged door between a patient room and an anteroom with balanced ventilation. The results are compared with laboratory experiments. The Overset Mesh method was used to model the door and the person moving between the rooms.
The simulations and the laboratory experiments for “door movement only” and “person exiting” the patient room showed very similar results. From the simulations for a person entering the patient room it was found that the air exchange is very sensitive to the velocity and the actual moving pattern of the person. The results show that the simulation model will enable reliable CFD simulations for more complicated cases in the future.
The simulation model will be used in the further work, which will include pressure differences between rooms, to investigate the sensitivity of walking speed and the movement of persons and to create simplified solutions to limit contamination from patient rooms.