SCALING PROPERTIES OF TRACER TRAJECTORIES IN A SATURATED POROUS-MEDIUM

The analysis of the trajectory's scaling properties of tracer particle s and preliminary valuations on their relation to experimentally deter mined dispersion coefficient tensor components in a saturated porous m edium are presented. The matching index technique is used to assure op tical access inside a three-dimensional laboratory model of a porous m edium. In this way it is possible to determine the trajectories of the tracer particles. Using the methods suggested by PIV (Particle Image Velocimetry), the test section is illuminated with a light sheet and i mages are acquired and digitalized by means of an acquisition apparatu s. A Lagrangian description of the motion is carried out and the stati stical analysis performed on the experimental field allows for the est imation of velocity probability density functions, velocity components correlation functions and components of the mechanic dispersion coeff icient tenser. The statistical analysis results are briefly recalled. The reconstructed tracer trajectories are analysed to verify the self- similarity or the self-affinity properties. The results show self-affi ne characteristics of the trajectories confirming the anisotropy of th e pollutant plume. A relation between the two components of the disper sion coefficient determined by the scaling analysis of the tracer part icles is derived.