A novel heterogeneity driven adaptive IMPES scheme for robust simulation of immiscible pollutant transport in complex aquifers for environmental protection

Numerical simulation of nonlinear properties in multiphase fluids within highly heterogeneous porous media remains a significant computational challenge. Traditional Implicit Pressure Explicit Saturation (IMPES) methods are typically hampered by strict stability constraints when dealing with high permeability contrasts, often resulting in inaccurate outcomes or prohibitive simulation times. To address these issues, a new adaptive IMPES strategy is developed, utilizing local heterogeneity to drive the stability level. The physical model, based on mass conservation and Darcy’s law, is implemented using the Cell-Centered Finite Volume Method (FVM) in a coupled framework. Numerical examples confirm that the proposed method reduces computational time by 40% while maintaining superior stability compared to existing techniques. The global mass balance error is strictly maintained below 10–6 , and the scheme effectively handles permeability variations up to 103 mD. This paper establishes a robust foundation for accurately modeling contaminant transport in complex geological formations, directly supporting sustainable groundwater management and environmental risk assessment.