Numerical simulation of transient flow development in a naturally ventilated room

Numerical simulations were conducted to model the transient flow development in a naturally ventilated space containing a centrally located localized source of heat. The simulations were compared with a series of small-scale laboratory experiments and existing theoretical models. The aim of the work was to benchmark CFD models for time-dependent buoyancy-driven natural ventilation against previously published experimental results and theoretical models. The simulations agree well with experimental results during the initial development of the room stratification. The CFD results accurately predict the maximum depth of the hot buoyant layer at the top of the room as well as the steady-state interface height which separates the warm upper buoyant layer from the cooler air below. The simulations also predict well the time taken for the buoyant upper layer to reach its maximum depth. However, at longer times the results diverge. This may be due to thermal diffusion and mixing at the interface between the upper and lower layers due to the inflow from the floor level vents.