HR: 0830h
AN: H11D-0889    [PDF]
TI: Numerical Modeling of Plumes Controlled by Transverse Dispersion
AU: Prommer, H
EM: Henning.Prommer@csiro.au
AF: TU Delft, Stevinweg 1, Delft, 2600GA Netherlands
AU: * Ham, P
EM: p.a.s.ham@citg.tudelft.nl
AF: TU Delft, Stevinweg 1, Delft, 2600GA Netherlands
AU: Schotting, R
EM: r.j.schotting@citg.tudelft.nl
AF: TU Delft, Stevinweg 1, Delft, 2600GA Netherlands
AB: Transversal mixing of reactants through dispersion and diffusion is in many cases the controlling factor for the attenuation of contaminants. For example, it is crucial for the supply of electron acceptors, or growth limiting nutrients, to plumes of biodegradable, oxidisable organic compounds. Indeed it has been experimentally and analytically proven that in situations where one electron acceptor dominates the degradation process, the stationary length of a plume can be quantified solely as a function of the transversal dispersion coefficient $\alpha_T$ and a few basic hydro(geo)logical parameters (Ham \textit{et al.}, 2003). Classical works (de Josselin de Jong, 1958; Bear, 1972) assume that the transversal dispersion coefficient consists of two terms: a molecular diffusion term and a hydrodynamic dispersion term. The latter is assumed to be a linear function of the flow velocity and the transversal dispersivity $\alpha_T$, where $\alpha_T$ is a constant. However, recent non-reactive and reactive laboratory-scale tank experiments by Olsson \textit{et al.} (2003) challenge this assumption. In this study a reactive multi-component transport code (PHT3D) is used in combination with statistical linear regression techniques for a detailed analysis of the experimental data and suggest a nonlinear velocity dependency for the dispersion term. The results indicate that the experimental data of the reactive transport experiment (concentration profiles of reactants, steady-state plume length) can be adequately described by the numerical model for a large range of velocities, when the nonlinear velocity dependency is employed in combination with a theoretically derived, representative single molecular diffusion coefficient.
DE: 1800 HYDROLOGY
DE: 1829 Groundwater hydrology
DE: 1831 Groundwater quality
DE: 1832 Groundwater transport
SC: Hydrology [H]
MN: 2003 Fall Meeting