LABORATORY OBSERVATION OF NONLOCAL DISPERSION

This work presents the results of a one-dimensional experimental inves tigation of contaminant transport in heterogeneous porous media. The u sual transport equations fail to adequately predict dispersion in such systems, and new theories to account for the distinctions have not ye t been examined experimentally. We use a one-dimensional porous media which is heterogeneous on the scale of observation to determine if the phenomena predicted by the new theories are observable. The experimen tal media are constructed from distinct layers of spherical glass bead s packed into cylindrical columns of Lucite. Flow was in the direction perpendicular to the layers. Dispersion was measured by recording the concentration of a chloride tracer as a function of time and position . The scale of measurement was finer than the scale of the heterogenei ty. The results show that the mixing between miscible fluids was affec ted by transitions-in the system parameters, before the transitions we re encountered by the mixing zone. This newly observed phenomenon has been interpreted as a nonlocal effect, and it begins to verify the new predictive theories.