HR: 11:35h
AN: H52D-06    [Abstracts]
TI: Modelling transport of decay chains by particle displacement along random trajectories
AU: * Cvetkovic, V
EM: vdc@kth.se
AF: Royal Institute of Technology, Dept of Water Resources Engineering, Brinellv. 32, Stockholm, SE-10044 Sweden
AU: Painter, S
H52D-06 AF: Center for Nuclear Waste Regulatory Analyses, Southwest Research Institute, P.O. Drawer 28510, San Antonio, TX 78228-0510 United States
AU: Frampton, A
H52D-06 AF: Royal Institute of Technology, Dept of Water Resources Engineering, Brinellv. 32, Stockholm, SE-10044 Sweden
AB: The streamtube/trajectory approach to modelling solute transport in the subsurface is widely used in applications, from numerical simulations (method of characteristics) to analytical models (Dagan). The trajectory approach has a solid foundation in chemical engineering and hydrodynamics. However, its main limitation is that the (semi)analytical solutions for incorporating retention processes, as proposed by Dagan and Cvetkovic among others, are applicable only to a single species partitioned into mobile and immobile phases. We propose a new methodology for simulating transport of multiple species (exemplified by decay chains) subject to random advection and retention in heterogeneous porous media. The method is based on displacing dynamically inert particles along random trajectories. We first demonstrate the accuracy of the method for a two-component chain with linear equilibrium sorption and hydrodynamic transport governed by the advection-dispersion equation, where an analytical solution is available. We then test the applicability of the method by considering a three- component decay chain in a two-dimensional fractured porous medium, where highly non-Gaussian advective transport has been simulated using a discrete fracture network model, and the retention processes are controlled by Fickian diffusion into the rock matrix. These tests in combination demonstrate that the proposed methodology is efficient and accurate, thus opening possibilities for studying transport of interacting species subject to more complex chemical reactions, where random advection and retention (Gaussian or non-Gaussian) can be fully incorporated into the modelling.
DE: 1832 Groundwater transport
DE: 1847 Modeling
DE: 1869 Stochastic hydrology
SC: Hydrology [H]
MN: Fall Meeting 2005