Validation of fire dynamics simulator predictions incorporating measured smoke characteristics – Part 2: Smoke concentration and detector characteristics in fires

Accurate prediction of smoke behavior is crucial in performance-based fire safety engineering, especially for assessing visibility reduction and smoke detection performance. This study investigates the predictive accuracy of the Fire Dynamics Simulator (FDS) in modeling smoke concentration and light attenuation in a mechanically ventilated full-scale compartment fire. Experiments were conducted using acrylonitrile butadiene styrene (ABS)—a thermoplastic known for its high smoke yield—and the results were compared with FDS simulations that incorporated different mass-specific extinction coefficients ( K m = 4.5, 7.7, and 8.7 m 2 /g). The simulation with K m = 7.7 m 2 /g, representing an experimentally validated value for ABS, showed the best agreement with measured smoke concentration and visibility. Comparisons revealed that to reach the same visibility threshold of 3.7 m, the simulation using K m = 4.5 m 2 /g required approximately 67% higher smoke concentration than the simulation using K m = 7.7 m 2 /g. These findings highlight the critical importance of selecting accurate, fuel-specific optical properties for smoke modeling. In particular, the appropriate specification of K m is essential to ensure reliable smoke prediction, tenability assessment, and smoke detector response in performance-based fire protection design, especially in complex, large-scale building environments.