COMPARISON OF NONLOCAL EULERIAN TO LAGRANGIAN MOMENTS FOR TRANSPORT IN AN ANISOTROPIC HETEROGENEOUS AQUIFER WITH DETERMINISTIC LINEAR NONEQUILIBRIUM SORPTION

An Eulerian perturbation scheme is applied to study transport of a rea ctive chemical experiencing linear nonequilibrium sorption with determ inistic rate constants in a heterogeneous porous medium. Exact solutio ns for the mean concentrations are used to obtain mean values of spati al moments through the third moments. Comparisons are made with result s obtained for the identical problem in a Lagrangian frame [Dagan and Cvetkovic, 1993]. If local-scale dispersion is neglected in the Euleri an analysis and the fully nonlocal flux is retained, then the Eulerian and Lagrangian moments agree. However, if either the Eulerian model i s localized or the local-scale dispersion is retained, then the moment s disagree. This disagreement is especially acute in the asymptotic li mits. If local-scale dispersion is included in the first-order Lagrang ian analysis, then one anticipates agreement through the third moments between the two approaches.