Free Boundary Conditions for Simulating Air Movement in a Big Hall Induced by a "Bare Cabin" Fire

Abstract

Air movement in a big hall induced by a fire in a "bare cabin" was simulated using Computational Fluid Dynamics (CFD). Applying CFD in simulat ing fire-induced air flow in buildings would require specification of free boundary conditions. Improper description of the free boundary conditions would give very different results. Three free boundary conditions commonly used were tested. Three sets of big hall geometry including two bare cabin designs and five heat re lease rates of fire of 20 kW m-1, 40 kW m -1, 60 kW m-1, 80 kW m-1, and 100 kW m-1 were considered. The self-developed program CY-TEAM modified from TEAM was selected as the simulator. Further, the commercial software CFX4.2 was used to compare with part of the results predicted by CY-TEAM. This gave a total number of 60 simulations. Results predicted from all these different geometries, conditions and software were compared. It is concluded that the free boundary condition should be specified carefully in simulating fire-induced air flow with CFD.