Effects of a Ventilation Duct on the Performance of a Fume Cupboard

When a fume cupboard is placed in a room with a ventilation duct, the air movement inside and around the fume cupboard is fully three-dimensional turbulent flow. However, in order to understand the fluid flow away from the fume cupboard a much simpler model can be used. This leads to a steady 20 model, with the computational domain including only the sash of the fume cupboard, the room and the entrance into the ventilation duct. In this paper we have used both the k-E turbulence model and the wall function technique to calculate the steady 20 turbulent fluid flow. In addition, a mathematical technique has been employed to map the simpler model onto the upper half of the complex plane, so that the complex potential can be found using a source and a sink on the real axis to represent the ventilation inlet and the exhaust outlet of the room, respectively. The objective of this paper is to reduce the cpu time by restricting the computational domain to a region which only includes the fume cupboard and a small region outside. We establish from a modified version of the potential flow a solution which we can use near the fume cupboard a a specified velocity boundary condition whilst solving the turbulent fluid flow model within the fume cupboard.