Dispersion of paramagnetic tracers in bead packs by T-1 mapping: Experiments and simulations

NMR imaging was used to study dispersion in 6 mm bead pack, T-1 maps were employed to measure the rate of axial spreading of paramagnetic tracers (GdCl3) inside the bead pack in the range of how rate from 0.015 mL/s to 0.175 mL/s. From the T-1 maps, tracer concentration profiles were obtained, which yielded dimensionless axial dispersion coefficient and mean transit time, Spatial variations in the dispersion coefficient were observed at flow rates above 0.08 mL/s, We hypothesized that the observed spatial oscillations in the dispersion coefficient arise from the spatial variations of the velocity distribution, To validate this mechanism we showed by simulation that similar dispersion coefficient variation occur in a layered network. Copyright (C) 1996 Elsevier Science Inc.