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...

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....

Recent advances in the development of large eddy simulation (LES) atmospheric models with corresponding transport and dispersion (AT&D) modeling capabilities have made it possible to simulate short, time-averaged, single realizations pollutant at spatial temporal resolution necessary for common needs, such as designing air sampling networks, assessing sensor system performance, characterizi...

A major contaminant transport process in soils is hydrodynamic dispersion by affecting the spreading and arrival of surface-applied pollutants at underlying groundwater reservoirs. When a soil unsaturated, very much affected water saturation. Centimeter- decimeter-scale column experiments were carried out to explore effects fluid saturation particle size on unsaturated solute dispersivity. Meas...

a r t i c l e i n f o The longitudinal dispersion coefficient (D) is an important parameter needed to describe the transport of solutes in rivers and streams. The dispersion coefficient is generally estimated from tracer studies but the method can be expensive and time consuming, especially for large rivers. A number of empirical relations are available to estimate the dispersion coefficient; h...

Recently the world’s population demographics crossed an important threshold: more people now live in urban than in rural areas (UN 2006). Projections show that the urbanization continues at a significant rate of ~ 1.5% per year, presenting difficult challenges of providing basic needs such as clean air, water and security for urban dwellers while managing available resources efficiently. In thi...

Computational fluid dynamics (CFD) is potentially a valuable tool for simulating the dispersion of air contaminants in workrooms. However, CFD-estimated airflow and contaminant concentration patterns have not always shown good agreement with experimental results. Thus, understanding the factors affecting the accuracy of such simulations is critical for their successful application in occupation...

In this paper, we develop a mechanism to detect, model and track the shape of a contaminant cloud boundary using air borne sensor swarms. The cloud consists of a transparent gas of nuclear, biological or chemical contaminants and is spreading slowly in an urban environment. A group of Uninhabited aerial vehicles (UAVs), having the required sensors, are made to fly through the cloud to detect th...

A hybrid analytical-numerical strategy based on the Generalized Integral Transform Technique (GITT) is used to solve steady-state multidimensional models for contaminants dispersion in rivers, streams and channels. The aim is to analyze and exploit this hybrid approach in the reduction of computational costs associated with convection-diffusion models that contain more than one space variable. ...