CFD modelling of the air and contaminant distribution in rooms

The k-ε model is a widely used model in engineering practice in handling indoor air quality problem. However, difficulties may arise when using the high Reynolds number k-ε model to simulate air flow patterns close to the boundaries of air and the stagnant component as well as the low air flow fluctuation elsewhere in a room. When using the k-ε model for low Reynolds number cases, the correlations between turbulent coefficients and turbulent Reynolds number must also be defined. By using the so-called Kolmogorov micro scale method, a new set of turbulent coefficient functions was deduced in this paper for the k-ε model in a case of low Reynolds number flow. Using the standard wall function leads to large differences between the measured and calculated heat transfer coefficient. A special wall function valid for a viscous sublayer, a buffer zone and a fully turbulent log-law zone is recommended in this paper. In addition, the modelling of air terminal devices in CFD simulations is summarized by using a literature collection.