In forensic fire investigations, computational modeling of the thermal response of gypsum board is critical for assessing the origin, duration, and intensity of fire events. This study aims to address the limitations of existing 1D models by developing a 3D model to simulate the coupled heat and mass transfer in gypsum board subjected to fire, enabling accurate predictions under non-uniform heat flux distribution. The model incorporates the complex thermochemical behavior of the reactive porous medium and is implemented using the finite volume method with a fully implicit Euler time integration scheme. After validation and verification, the model is employed to investigate the thermal response of gypsum board under various heat flux configurations, including stepwise, linearly increasing, and Gaussian distributions. A comparative analysis of lateral and vertical gradients in temperature and species concentration at the slab center is performed to evaluate the effects of spatially varying heat fluxes. Results demonstrate that while the 1D model is adequate for uniform heating scenarios, 3D effects become increasingly significant with steeper heat flux gradients. Under non-uniform and non-linear flux profiles, a 3D model is essential for accurately capturing the spatial complexity of the calcination process. The rationale for this work stems from the need for more comprehensive tools in forensic investigations, where non-uniform exposures dominate, and to our knowledge, this is the first study to present a fully three-dimensional model capable of simulating the response of gypsum board under non-uniform fire exposure, providing detailed lateral profiles for enhanced fire pattern analysis.
(Publisher abstract provided.)