The effect of ventilation and sash handles on the flow in fume cupboards.

Two-dimensional numerical simulations have been undertaken for the steady turbulent fluid flow in a room containing a fume cupboard which is attached to a wall and a ventilation duct which is situated in the ceiling of the room, see figure 1. The wall opposite to the fume cupboard is assumed to be porous and a fully developed fluid velocity profile is applied far upstream. The calculated flow is considered to be that which is actually found in the central plane of a practical fume cupboard. The fume cupboard sash is fixed in its maximum opening position at 0.5m, and whilst various positions and fluxes of the ventilation duct are considered, a constant fume cupboard face velocity is maintained by suitably choosing the fluid flow through the porous wall. The fluid flows, both inside the fume cupboard and the room, are obtained using a 2D ke turbulence model and the wall function technique within the commercial software package FLUENT. We use the length L to denote the horizontal distance along the ceiling of the room from the wall containing the fume cupboard to the ventilation duct. To improve the convergence of the fluid flow the solution domain was divided into two regions, one inside the fume cupboard, the inner region, and the other outside, the outer region, with an overlap in the vicinity