Mixing is receiving increased attention in hydrological literature because it controls the rate o... more Mixing is receiving increased attention in hydrological literature because it controls the rate of fast chemical reactions, which demands a conceptually accurate description of transport. Specifically, conceptually accurate transport requires acknowledging differences between mixing and spreading, which are equated in the ADE. Effective transport equations based on non-local formulations can provide such a separation but introduce additional parameters that must
Transport in subsurface environments is conditioned by physical and chemical pro- cesses in inter... more Transport in subsurface environments is conditioned by physical and chemical pro- cesses in interaction. Because of the complexity of the problem, very simple models have been set up bypassing most of the medium heterogeneity as well as the non- linearities of the chemical reactions. Recent observations have shown first that the multi-scale medium heterogeneity can dramatically change subsurface flow and the bulk transport properties. Secondly, growing evidences suggest that several contam- inants adsorb kinetically and non-linearly onto the aquifer solids. We aim at deter- mining the bulk transport laws of such kinetically and non-linearly sorbing solutes in heterogeneous media. The key problem is to simulate this coupled problem. Because of the widely-scattered heterogeneity, the transport equation cannot be solved analyt- ically. We thus set up a new efficient and flexible numerical approach. This approach, called "precipiton" model, is based on a method used by geomorphologs for modeling erosion/sedimentation. It consists first in a spatial discretization of the transport equa- tion and secondly in a Lagrangian formulation through the use of a particle tracking method. The precipiton method is efficient because it generalizes the particle track- ing scheme for chemically active solutes. The precipiton method is flexible because it achieves a decoupling of the physico-chemical process at the precipiton scale, i.e. at the lowest scale, thus enabling the modeling of virtually all possible chemical reac- tions. Thanks to this numerical tool, we can derive the spatio-temporal evolution of the solute plume and address the following field issues: - Does the physical medium het- erogeneity modify the expression of the chemical reaction from the laboratory scale to the field scale? (upscaling problem) - The physical heterogeneity and the chemi- cal reaction have similar effects a priori: they slow down the plume evolution. Is it possible to distinguish from breakthrough curves and possibly other observables the effects of the physical heterogeneity and of the chemical reaction? How do physical and chemical processes affect the bulk solute transport predictions? (direct problem) - Is it possible to infer the elementary chemical reaction from a breakthrough curve and/or moments? (inverse problem)
Mixing is receiving increased attention in hydrological literature because it controls the rate o... more Mixing is receiving increased attention in hydrological literature because it controls the rate of fast chemical reactions, which demands a conceptually accurate description of transport. Specifically, conceptually accurate transport requires acknowledging differences between mixing and spreading, which are equated in the ADE. Effective transport equations based on non-local formulations can provide such a separation but introduce additional parameters that must
Transport in subsurface environments is conditioned by physical and chemical pro- cesses in inter... more Transport in subsurface environments is conditioned by physical and chemical pro- cesses in interaction. Because of the complexity of the problem, very simple models have been set up bypassing most of the medium heterogeneity as well as the non- linearities of the chemical reactions. Recent observations have shown first that the multi-scale medium heterogeneity can dramatically change subsurface flow and the bulk transport properties. Secondly, growing evidences suggest that several contam- inants adsorb kinetically and non-linearly onto the aquifer solids. We aim at deter- mining the bulk transport laws of such kinetically and non-linearly sorbing solutes in heterogeneous media. The key problem is to simulate this coupled problem. Because of the widely-scattered heterogeneity, the transport equation cannot be solved analyt- ically. We thus set up a new efficient and flexible numerical approach. This approach, called "precipiton" model, is based on a method used by geomorphologs for modeling erosion/sedimentation. It consists first in a spatial discretization of the transport equa- tion and secondly in a Lagrangian formulation through the use of a particle tracking method. The precipiton method is efficient because it generalizes the particle track- ing scheme for chemically active solutes. The precipiton method is flexible because it achieves a decoupling of the physico-chemical process at the precipiton scale, i.e. at the lowest scale, thus enabling the modeling of virtually all possible chemical reac- tions. Thanks to this numerical tool, we can derive the spatio-temporal evolution of the solute plume and address the following field issues: - Does the physical medium het- erogeneity modify the expression of the chemical reaction from the laboratory scale to the field scale? (upscaling problem) - The physical heterogeneity and the chemi- cal reaction have similar effects a priori: they slow down the plume evolution. Is it possible to distinguish from breakthrough curves and possibly other observables the effects of the physical heterogeneity and of the chemical reaction? How do physical and chemical processes affect the bulk solute transport predictions? (direct problem) - Is it possible to infer the elementary chemical reaction from a breakthrough curve and/or moments? (inverse problem)
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Papers by Philippe Davy