Comparison of Subgrid Scale Models in Large-Eddy Simulation of Fire Dynamics

This paper evaluates the subgrid scale (SGS) models of Large-Eddy Simulation (LES) in the Fire Dynamics Simulator (FDS), which is the Computational Fluid Dynamics (CFD) code developed at the National Institute of Standards and Technology (KIST) for practical use. LES results of three SGS models (Smagorinsky model, Structure-Function model and WALE model) are compared to fire experimental data of fully developed flow fields in a compartment with an opening. On the other hand, the influence of the three SGS models on transient flow fields at an initial stage of compartment fire phenomena was investigated in terms of time evolution of the temperature by a heat detector model. Further, it is employed to study the effect of the SGS models on unsteady flow fields with simple harmonic oscillation, which is used as a very simplified model of ship rolling motion. From the numerical simulations, it is found that there is no critical difference between the results by the above SGS models. This leads to the conclusion that the Smagorinsky model, which is adopted in FDS by default, works well in practical fire dynamics simulations though it is a primitive SGS model in comparison with the other two improved models.