Barr, A.D., Townley, L.R., and Endres, A.L. (1999), A numerical quasi-three-dimensional model for simulating large-scale stable dense miscible plumes in aquifers, Proceedings of Contaminated Site Remediation: Challenges posed by urban and industrial contaminants, 21-25 March 1999, Fremantle WA, 267-73.

Numerical models of dense solute transport in porous media can be classified based on dimensionality and assumptions used in constructing the models (e.g., three-dimensional, two-dimensional in plan). Each category has advantages and disadvantages. The larger the dimensionality of the model, the greater the expense in terms of both computer storage and computer processing. The smaller the dimensionality, the less detail that can be incorporated in the simulations. This paper describes an intermediate technique for simulating a dense miscible groundwater plume in an aquifer, based on a quasi-three-dimensional method. This technique has the advantage of reducing computational expenses compared with fully-three-dimensional models, whilst retaining some of the complexity of three dimensions lost in two-dimensional models. A similar approach has already been used for immiscible fluids (e.g., Essaid, 1990). Our method is based on dividing the aquifer into a number of layers. It is assumed that the vertical concentration gradient in each layer is small and can be ignored. A simple model illustrates the technique using two layers for groundwater flow and multiple layers for solute transport.