Dense Non-Aqueous Phase Liquid (DNAPL) contaminants, which are immiscible with water and denser than it, are considered among the most significant sources of persistent contamination in subsurface and porous environments. The analysis of contaminant transport in porous media constitutes the main focus of this study, which aims to develop a practical and efficient numerical approach for predicting, controlling, and modeling the behavior of DNAPL contaminants. In this regard, efforts have been made to simulate, with acceptable accuracy, the spatial and temporal distribution, magnitude, and spreading pattern of contaminants within porous media.
In this research, the Differential Quadrature Method (DQM) was employed as a high- accuracy discretization technique with relatively low computational cost to numerically simulate the movement of DNAPL contaminants in porous media. The model was implemented in the Matlab software environment. The simulation and analysis of water pressure, DNAPL pressure, and DNAPL saturation percentage— considering the physical properties of the contaminant and the characteristics of the porous medium—using the Differential Quadrature Method represent key achievements of this study.
The validation results indicate that the DQM model implemented in the DQM- DNAPL framework is capable of accurately reproducing the dominant behavior of DNAPL infiltration. A strong agreement was observed in the saturation distribution and its variation trends along depth, radial direction, and time. The temporal evolution demonstrates a gradual and predominantly downward migration of contamination under the dominance of gravitational forces, with the system approaching a quasi-steady state over long time periods. Furthermore, density was identified as the primary controlling factor governing penetration depth, viscosity as the parameter regulating mobility and lateral spreading, and porosity as the component influencing the extent and concentration of contamination.