Computational fluid dynamics modelling of fire

Abstract

An overview of a methodology for simulating fires and other thermally-driven, low-speed flows is presented. The model employs a number of simplifications of the governing equations that allow for relatively fast simulations of practical fire scenarios. The hydrodynamic model consists of the low Mach number large-eddy simulation subgrid closure with either a constant or dynamic coefficient eddy diffusivity. Combustion is typically treated as a mixing-controlled, single-step reaction of fuel and oxygen. The radiation transport equation is written in terms of a spectrally-averaged grey gas. Applications of the model include the design of fire protection systems in buildings and the reconstruction of actual fires.

Keywords:

• combustion
• fire
• large-eddy simulation
• low Mach number approximation
• lumped species
• thermal radiation

Acknowledgement

The authors would like to thank Sheldon Tieszen of Sandia National Laboratories for providing measurement data on the methane pool fire experiments. The authors would also like to thank William Mell, Timo Korhonen and Ronald Rehm for their contributions to the development of FDS.