To achieve better precision in describing contaminant dispersion in channels some authors resort to dividing a channel into two zones, fast and slow, leading to a pair of coupled evolution equations for cross-sectionally-averaged concentrations in the zones. We construct a two-zone model whose accuracy is guaranteed by centre manifold theory. The model leads to evolution equations that differ f...

This paper is an overview of some of the methods developed by the Team for Advanced Flow Simulation and Modeling (THAFSM) [http://www.mems.rice.edu/TAFSM/] to support ̄ow simulation and modeling in a number of ``Targeted Challenges''. The ``Targeted Challenges'' include unsteady ̄ows with interfaces, ̄uid±object and ̄uid±structure interactions, airdrop systems, and air circulation and contamina...

Based on the grey theory, grey characters of river environment system are analyzed, the velocity and dispersion coefficient and attenuation in river are considered as uncertainty parameters and expressed as gray parameters. A grey differential equation of contaminant diffusion in river is built. And the equation has special structure. The truncation error of finite differential method in solvin...

Small angle neutron scattering (SANS) data are reported from a system that models the contamination of a clay/organic matter soil from a fuel spillage. The soil was represented as an aqueous dispersion of the synthetic clay mineral Laponite coated with lysine, and the contaminant was a representative jet fuel, quadricyclane, mixed with the detergent cetyltrimethylammonium bromide (CTAB). The ad...

The ARGOS decision support system is currently being extended to enable estimation of the consequences of terror attacks involving chemical, biological, nuclear and radiological substances. This paper presents elements of the framework that will be applied in ARGOS to calculate the dose contributions from contaminants dispersed in the atmosphere after a 'dirty bomb' explosion. Conceptual method...

Mixing-transport of solute entering at sinkholes or from within the limestone matrix in cavernous conduits is an important process for contaminant migration in karst aquifers. This process may be described with a one-dimensional advection-dispersion equation incorporating the fluxes of solute and water across the conduit wall. For the dilution-dispersion equation, which does not include solute ...

A Monte Carlo analysis is used to quantify environmental parametric uncertainty in a multi-segment, multi-chemical model of the Venice Lagoon. Scientific knowledge, expert judgment and observational data are used to formulate prior probability distributions that characterize the uncertainty pertaining to 43 environmental system parameters. The propagation of this uncertainty through the model i...

The present work solves two-dimensional Advection-Dispersion Equation (ADE) in a semi-infinite domain. A variable source concentration is regarded as the monotonic decreasing function at the source boundary (x=0). Depth-dependent variables are considered to incorporate real life situations in this modeling study, with zero flux condition assumed to occur at the exit boundary of the domain, i.e....

Diffusion and dispersion in Choba Creek were monitored using modeling simulation under the influence of velocity. The study process arsenic deposition at various discharge stations, where contaminant was observed depositing different levels concentration. This implies that quality water creek has deposited as a substance environment, application monitoring diffusion rate are based on heterogene...

The transport mechanism of contaminated groundwater has been a problematic issue for many decades, mainly due to the bad impact of the contaminants on the quality of the groundwater system. In this paper, the exact solution of two-dimensional advection-dispersion equation (ADE) is derived for a semi-infinite porous media with spatially dependent initial and uniform/flux boundary conditions. The...