Large Eddy Simulation of Air Escape through a Hospital Isolation Room Single Hinged Doorway—Validation by Using Tracer Gases and Simulated Smoke Videos

Saarinen, Pekka E.; Kalliomäki, Petri; Tang, Julian W.; Koskela, Hannu

There are a few earlier studies reporting LES modelling of contaminant transport caused by door movement and passage through the doorway. Choi and Edwards [29] simulated a walking manikin going through an open doorway (i.e. in the absence of a door). In this study, they use their own immersed solid method [30] to model a walking human. They modelled several scenarios, varying the walking speed, initial position of the manikin, and initial distribution of the contaminant in the two rooms. The contaminant in their study consisted of particles, affected by gravity. The numerical methods used to solve the transport equations were also developed by the authors. In a later paper the same authors [31] simulated a more complex geometry, where a human is walking from a contaminated room to a clean room through a vestibule and two hinged or sliding doors. This simulation also includes ventilation (with an exhaust in the vestibule and small gaps below the doors), human plume, and several successive passages through the doors, with a gaseous contaminant. A clear advantage of the immersed solid methods is that they do not require re-meshing between the time steps, thereby allowing use of a large computational mesh. A study by Shih et al (case B in [32] ), applied dynamic meshing to model the effect of opening and closing of a sliding door, without passage, on the spread of CO 2 contaminant from a human source inside a negative-pressure isolation room. Since dynamic meshing is computationally heavier than the immersed solid technique, the size of the mesh was less than 100 000 cells, though it was enough to model the CO 2 isosurfaces.