Speaker: Narges Dashtbesh
Date: Thursday 23rd of June 2022, 1:15 pm.
Abstract:
Understanding and modelling contaminant transport is necessary to assess the lifetime of pollution sources and their severity and optimize the remediation strategies. The transfer of contaminants from the NAPL (Non-Aqueous Phase Liquid) phase to the aquifer is a multi-scale problem driven by mass transfer between both phases and is generally described by local non-equilibrium models. While the mass exchange coefficient, an important property in such models, play a key role in the fate of the pollution source, it is usually approximated by a constant value estimated from empirical correlations. However, it generally shows a transient behaviour and can evolve with NAPL phase composition and relative solubilities, which remains poorly studied. In this work, we upscale numerically this effective property from 2D pore-scale numerical simulations. We study the impact of different factors on the form and behaviour of the mass exchange coefficient in the presence of a multi-component NAPL source depending on whether the internal mass transfer is limiting. The potential implications of replacing this time-and-space-dependent mass transfer coefficient with a constant and unique value are discussed.