CFD Simulation of Smoke Dispersion in Underground Parking Garages

Abstract

This study presents a three dimensional Computational Fluid Dynamics (CFD) investigation of smoke propagation and thermal behavior in an underground parking garage equipped with a jet fan based mechanical ventilation system during a single representative multi vehicle fire event, in which three motorcycles ignite in sequence in a car park shared by cars and motorcycles. The simulation is implemented using the open source platform OpenFOAM, utilizing the buoyantPimpleFoam solver to incorporate buoyancy driven flow, heat transfer, and passive scalar smoke transport. The geometric configuration is based on a full scale underground parking facility, including structural elements, ventilation ducts, jet fans, and defined volumetric heat release zones to represent the fire source. Turbulence effects are captured using the k-ω SST model to simulate complex flow separation and recirculation induced by jet fans. The simulation results provide detailed temporal and spatial distributions of velocity, temperature, and smoke concentration. The temperature above the fire reaches a peak of 155.1 ◦C, whereas at the breathing height of 1.7 m the 60 ◦C limit is exceeded only in the immediate vicinity of the burning motorcycles. The floor area covered by dense smoke (normalised concentration ϕ > 0.1) peaks at 1.51% at t = 150 s and falls to 0.01% at t = 270 s, while the smoke concentration at the entrance remains below 0.4% of the source value. Quantitative analysis demonstrates that the ventilation system enhances smoke transport toward exhaust ducts, mitigates overall smoke accumulation within the parking space, and maintains the selected thermal and smoke criteria for the duration of the considered fire event. The proposed workflow provides a reproducible framework for evaluating jet fan configurations and smoke control strategies, focusing on ventilation performance and smoke transport rather than detailed combustion modeling.