<p>Internal instability in hydraulic structures manifests in various ways, with internal erosion, particularly suffusion, being a primary cause of failures in earthen structures. Suffusion involves the detachment and transport of particles through a granular medium’s pores. While many studies have focused on suffusion in homogeneous soils, few have explored soils with heterogeneities. This study aims to modelize suffusion mechanisms in soils exhibiting structural heterogeneity in layers (central, downstream) and examine their impact on suffusion initiation and development. The numerical involves a finite element simulation, enabling the modeling of suffusion experiments using Comsol software. This approach seeks to characterize the impact of granular heterogeneities on variably saturated soil vulnerability to suffusion and assess the effect of each layer and their interaction in this process. After detailing the numerical model, including initial and boundary conditions and the adopted retention models, the suffusion simulation is described and developed. Furthermore, this study utilizes Monte Carlo simulation for stochastic testing, to analyze suffusion in soils with central heterogeneity. By integrating random variations, the study enhances the understanding of suffusion mechanisms and validates the numerical approach using experimental data. The Mean Relative Error (MRE) of the model was found to be 4.97%, indicating a strong fitting with the experimental results. The results are presented and discussed, demonstrating agreement between numerical results and experimental data, thereby validating the adopted numerical approach. The numerical model reproduces infiltration flow and internal erosion in an unsaturated heterogeneous soil, providing crucial insights into the behavior of suffusion in such soils and contributing to the development of more effective erosion mitigation strategies in geotechnical engineering.</p>