CFD Modeling of Tunnel Fires

Abstract

Computational fluid dynamics (CFD) modeling has been widely used for performance-based tunnel fire safety design in engineering applications. A CFD tool divides a computation domain into a large number of small cells, and solves a set of differential equations with sub-models using different solution algorithms. The CFD users need to not only efficiently use CFD tools, but also to understand the embedded mechanisms. The basics of CFD modeling are introduced including controlling equations, different turbulence models, and numerical methods. Sub-models important for tunnel fires are then described, that is gas phase combustion models, condensed phase pyrolysis models, fire suppression models, wall functions, and heat transfer models. Despite the rapid development and completeness of these models related to fire phenomena, many limitations exist which should be always kept in mind by the users. Recommendations for CFD modeling of tunnel fires are presented.