Diffusion of solute in soil media

Diffusion is the process by which matter is transported from one part of a system to another as a result of random moleculer motion (Crank, 1957). Fick's law is used to simulate the rate of the diffusive mass transport (Crank, 1957; Kirkham and Powers, 1972). Combining Fick's law with the law of mass conservation produces a parabolic partial differential equation (PDE) for simulating diffusive mass transport under transient conditions (Allen III et al., 1988; Crank, 1957). Numerical and analytical solutions of the PDE were developed for a collection of initial and boundary conditions. This program demonstrates the one-dimensional spreading of a chemical plume of initial width h in a semi-infinite system with an initial concentration of zero. The diffusion process is illustrated graphically for user-selected times.

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Last Modified: January 16, 2008.