Methods of handling non-homogeneities at different scales in radionuclide transport
Past work in the field of transport of water borne contaminants in spatially random porous media has been reviewed, for the period from 1921, in which G.I. Taylor developed some basic ideas of the subject, up to 1988. This therefore includes the modern advances of Dagan, Gelhar and co-workers who considered the transport equation as a stochastic differential equation and were thereby able to give a reasonable explanation of the scale-dependence phenomenon. The report continues with a description of a new approach to radionuclide transport in fractured rock. An angular distribution function is introduced which takes into account the random lengths and orientation of fractures. Such fracture lengths are considered to be analogous to mean free paths, and the random direction of motion of a marked particle when it meets an intersection of two fractures is analogous to a scattering event. By means of this analogy, a Boltzmann-like equation similar to that employed for neutron transport can be used. Numerical and analytical solutions of this equation have been obtained and the results highlight the inadequacies of the classical advection-dispersion theory and also explain the scale-dependence of the dispersion length noted by experimentalists.
Bibliographic Reference: EUR 14696 EN (1993) 84 pp., FS, ECU 11.50
ISBN: ISBN 92-826-5822-8
Record Number: 199310834 / Last updated on: 1994-11-29
Original language: en
Available languages: en