InterPore2026

Assessment of 1D averaged model for prediction NAPL contamination in heterogeneous media

21 May 2026, 10:05

1h 30m

Poster Presentation (MS05) Physics of multiphase flow in diverse porous media Poster

Speaker

Anne-Julie Tinet (GeoRessources - Université de Lorraine)

Description

In the context of soil contamination by NAPLs (Non Aqueous Phase Liquids) and planification of remediation, understanding of the behaviour of the source zone, particularly its lifetime and to development of the contaminated plume, is essential. The use of predictive modeling is therefore necessary, as it allows the lifespan of the pollution source and/or its impact to be estimated in the various scenarios considered by describing the temporal evolution of the mass of pollutant in the source, the flow emitted by it, and the concentrations in the impacted environments.
Classic numerical models (e.g. Côme et al. 2007) used to describe source zone behaviour are usually quite complex and require numerous parameters. Indeed, source areas are characterized by various scales of heterogeneity, and mitigation mechanisms in this context can become strongly coupled, making it difficult to describe average behavior at the source area level in simple terms. These models are also fraught with numerous uncertainties given the generally fragmented knowledge of the system being modeled. While conducting 3D modeling that takes into account most mitigation mechanisms and incorporates uncertainty quantification is very time consuming, the adoption of simplified models would facilitate the uncertainty assessment stage and reduce the time required to complete the modeling. Simplified models already exists under certains hypotheses such as low Damköhler with simple heterogeneity distribution (Mabiala et al. 2003), local equilibrium (Quintard & Whitaker, 1994; Guo et al. 2018). The aim of this work is study the capacity of simplified models to describe the source zone behaviour for a larger range of heterogeneity distribution, at low Damköhler, consistent with the conditions generally encountered in polluted sites and soils.
To this end, extending the work of Guo et al. (2021), a large 2D model, developed in Comsol Multiphysics, and an averaged 1D model were applied to the dissolution of a hydrocarbon source zone in a heterogeneous environment. Different configurations, with increasing degrees of complexity, were tested, starting with a stratified medium, then a periodic bimodal heterogeneous medium, and finally a spatially correlated random medium. The heterogeneities are characterised by varying values of permeability and solubilisation transfer coefficient. Averaged curves for solute concentration and phase saturation were compared between both models to assess both the plume development and the source lifetime.
In general, the large-scale averaged model performs well as long as the low Damköhler number assumption is verified, particularly with regard to concentrations. Results show that the ratio of transfer coefficient is a rather sensitive parameter, especially in regards to the source lifetime prediction with a good performance of the upscaled model for ratios up to 10.