Numerical simulations on balcony spill plume

Balcony spill plumes were studied by computational fluid dynamics (CFD). Reference was made to the scale model studies reported by Morgan and co-workers in which an atrium hood adjacent to a fire compartment was considered. Mechanical smoke extraction through a vertical air duct was also studied. Six sets of simulations were carried out and are reported in this paper. The computing domains of each simulation were extended outside the model geometry so that the free boundary condition could be treated properly. It was found that the free boundary conditions have to be specified carefully in carrying out CFD simulations, especially for cases where pressure distributions are important. The neutral plane heights under different extraction rates were studied. From the CFD studies, the neutral plane heights moved up when extraction rates increased. Further, a real life scenario on designing a smoke control system for a super tall atrium using CFD was briefly outlined.