CFD Modeling of Smoke Movement in an Atrium

Robin Wu


The purpose of this paper is to better understand the behavior of smoke movement in an atrium. Thus gives first responders and civilians in and out of building a better understanding

With the advancements of modern technology, computers and softwares make simulation models possible such as fire models to simulate fire and smoke movements. In this paper, a computational fluid dynamic (CFD) software Fire Dynamic Simulator (FDS) is used to conduct a series of atrium tests to investigate the effectiveness of smoke exhaust systems. FDS solves the Navier-Stokes equations appropriate for low speed flows (Ma < 0.3) with an emphasis on smoke, heat transport and CO2 concentrations from fires. The default turbulence model used in FDS simulation is the Large Eddy Simulation (LES), which is the solution of Navier-Stokes equations at low speed.

The compartment tested was 9 m × 6 m × 5.5 m height which is the same conditions used in Hadjisophocleous, Fu, and Lougheed [6]. In their paper, the measured exhaust rates used ranged from 2.0 to 5.0 kg/s with thermocouples placed at various heights to see the upper smoke layer and the lower air layer along with the convective boundary layer or interface layer. CO2 concentrations, heat release rates, and temperatures are looked at to better understand the behavior of smoke. Keep in mind that this is only a short term test of 1300 seconds of simulations time. Also note that FDS does not simulate the burning of materials. There are other softwares like CFAST and PyroSim would better support this. FDS also does not consider flashovers.

FDS applies Deardorff’s turbulence model [3] and Smagorinksy model [14] to predict the CO2 concentration, upper smoke layer and temperatures. Both these models are briefly described in this paper with focus on fluid flow at low speeds. The results from the model

of best ways to save lives and to minimize losses due to fire or smoke damages.

are compared to the experimental results by Hadjisophocleous, Fu, and Lougheed [6] to see if the CO2 concentrations and heat release rates are similar.