Methodical approaches used in the computational model “PROLOG” are given in the paper. This model is intended for assessing radiological situations and an efficiency of counter measures after short term radioactive releases. Basic local Gaussian dispersion algorithm is supplemented with modules for assessing a plume rise, dry deposition velocities, effect of buildings and complex terrain, etc. ...

The characteristics of solute transport within log-conductivity fields represented by power-law semi-variograms are investigated by an analytical Lagrangian approach that accounts for the automatic frequency cut-off induced by the initial contaminant plume size. The transport process anomaly is critically controlled by the magnitude of the Péclet number. Interestingly enough, unlike the case of...

The release of a harmful contaminant into a densely populated area could quickly affect significant numbers of people. The results of a physical modeling study of the atmospheric transport and dispersion of a hypothetical chlorine release are presented as a case study for situational awareness and preparedness planning. Both a Computational Fluid Dynamics (CFD) model and a rapid response model ...

In this paper a time-splitting technique for the two dimensional advectiondispersion equation is proposed. A high resolution in space Godunov method for advection is combined with the RT0 Mixed Finite Element for the discretization of the dispersion term. Numerical tests on an analytical one dimensional example ascertain the convergence properties of the scheme. At di erent Peclet numbers, the ...

A high resolution grid-free vortex filament scheme is applied to the prediction and simulation of coflowing round jets with a view to acquiring a new perspective on their physics and establishing the validity of the numerical technique. Vortex loop removal at inertial range scales provides a nondiffusive model of local dissipation that remains compatible with the presence of backscatter. Consis...

Turbulent bursting events play a major role in natural systems in terms of sediment scour, transport and accretion as well as contaminant mixing and dispersion. The "bursts" were extensively studied in laboratory experiments under steady flow conditions, but rarely tested in unsteady natural flows. Herein a technique is described for the detection and analysis of turbulent events within large c...

Analytical solutions are widely used as screening tools for estimating the potential for contaminant transport in groundwater, or for interpreting tracer tests or groundwater quality data. A solution for three-dimensional solute migration from a plane-source source that is frequently used in practice is the approximate solution of Domenico [J. Hydrol. 91 (1987) 49-58]. A more rigorous solution ...

We present a sequence of purely advective transport models that demonstrate the influence of small-scale geometric inhomogeneities on contaminant transport in fractured crystalline rock. Special weight is placed on the role of statistically generated variable fracture apertures. The fracture network geometry and the aperture distribution are based on information from an in situ radionuclide ret...

The basic model motivating this work is that of contaminant transport in the Earth’s subsurface, which contains layers analytical and semi-analytical solutions corresponding advection–dispersion equations could be derived. Then, using interface relations between adjacent layers, one can streamline study to solution initial boundary value problem for a coupled parabolic system on partitioned dom...

This research describes the goals, design and implementation of a quasi natural gradient, laboratory scale, sand tank (aquifer) model experiment. The model was used to study the transport of an inorganic tracer (Chloride) in groundwater, within a tropical aquifer (porous medium) material. Three-dimensional sand tank (1.8 m × 0.3 m × 0.8 m) experiments were conducted to investigate contaminant t...