Because of mesh conditions, the Reynolds numbers range studied
(1 < Re < 800) induces computational limitations. This problem,
particularly sensitive for convection-diffusion calculations, is here
overcome by diffusion coefficient scaling. As a consequence,
recirculation effects are first investigated for model species (D >
10-9 m2 s-1) and then studied in the case of species with lower
diffusion coefficients. Finally, experimental studies on the mixing
of species at different flow rates are reported that show the same
tendency regarding the hydrodynamic effects.