Simulations of Fire Smoke Movement in High-rise Buildings with FDS

Abstract

The Fire Dynamics Simulator (FDS) developed by the National Institute of Standards and Technology (NIST) solves a form of the Navier-Stokes equations appropriate for low-speed (Ma < 0.3), thermally-driven flow with an emphasis on smoke and heat transport and has been shown to be capable of simulating the flow and temperature conditions in the vicinity of a fire [1]. In the present study, we evaluate the ability of FDS to simulate pressure dynamics in high-rise buildings, a pre-requisite to the correct simulation of smoke transport far from the fire.The objective of this study is to test the accuracy of FDS for determining the conditions throughout the entire expanse of a 40-story high-rise building featuring an elevator shaft and four stairwells. The output from FDS is first compared to the results generated by a network model called COSMO. The comparison of the two outputs shows that correct results are predicted by FDS. Additionally, more realistic scenarios are simulated with FDS and the results are compared with those of a network model called CONTAM and an in-house MATLAB program. The network model CONTAM and the MATLAB program do not represent the time-dependent thermal mixing process taking place inside the elevator shaft and the stairwells whereas FDS does. The comparison shows the importance of this thermal mixing process that impacts the pressure dynamics and smoke movement inside the building, with implications for the evacuation capability provided by the stairwells.