A hybrid numerical model for simulating atmospheric contaminant dispersion is developed. The hybrid numerical scheme employs an hp-adaptive finite element method coupled with a Lagrangian particle transport technique to solve the governing equations for atmospheric flow and species transport. A random walk/stochastic approach is used to generate Lagrangian particles that define the contaminant ...

Current simulation tools of airflow and contaminant dispersion in built environment cannot provide detailed information with little computing effort, which is critical for emergency management. Multizone airflow network models are fast but cannot provide detailed flow and contaminant transport information in an indoor space. Computational Fluid Dynamics (CFD), on the other hand, gives very deta...

Purely stochastic methods can yield useful prediction models of contaminant arrival-time distributions derived from advective-dispersive transport in a variety of one-dimensional environments. Two different models are considered, both relating to dispersion of a brief pulse of conservative contaminant in a steady flow system. The first model considers the arrival-time of a contaminant pulse in ...

Following a toxic contaminant release, either accidental or intentional, predicting the transport and dispersion of the contaminant becomes a critical problem for Homeland Defense and DoD agencies. To produce accurate predictions requires characterizing both the source of hazardous material and the local meteorological conditions. Decision makers use information on contaminant source location a...

A mathematical method called subordination broadens the applicability of the classical advection--dispersion equation for contaminant transport. In this method, the time variable is randomized to represent the operational time experienced by different particles. In a highly heterogeneous aquifer, the operational time captures the fractal properties of the medium. This leads to a simple, parsimo...

A modified one-dimensional Danckwerts convection-dispersion-reaction (CDR) model is numerically simulated to explain the observed chlorine residual loss for a "slug" of reactive contaminants instantaneously introduced into a drinking water pipe of assumed no or negligible wall demand. In response to longitudinal dispersion, a contaminant propagates into the bulk phase where it reacts with disin...

A contamination source identification problem in constant porous media flow is addressed by solving the advection-dispersion equation (ADE) with a hierarchical Bayesian computation method backward through time. The contaminant concentration is modeled as a pair-wise Markov Random Field (MRF) and the distribution is updated using current concentration measurements at finite locations. Hierarchic...

it is well known that, contaminant transportation is a major problem in coastal zones and has to be faced when coastal structures are being planned. sea pollution not only causes environmental damage, but also impacts quality and population of sea resources. oil is the most important pollutant, pollutants emanating from industries, ships, drilling and exploration in the seabed, ship sewage, tox...