scope:

ABSTRACT

The focus of this study is to outline the general requirements to accurately simulate the air quality in the breathing zone of a person using CFD when steep gradients of velocity, temperature, and contaminants are present near the person. In particular, these steep gradients may result from the presence of personal ventilation devices, or from body-emitted bio-effluents. Two configurations are discussed in the paper: a person sitting in an infinite domain with no nearby ventilation system (buoyancy-driven flow alone), and the case of a person sitting in a room with a combined displacement and personal ventilation system. The latter case compares the computational results with test data for validation purposes. Issues discussed in this paper include: (1) the importance of proper physical representation of the person near the breathing zone including the shoulders, neck and chin, (2) the effects of the thermal boundary conditions, and (3) the effect of grid resolution. CFD results are obtained using the steady Reynolds- Averaged Navier-Stokes (RANS) method with the k-ε and k-ω families of turbulence models.