The effect of the periodic
step (s) on the mixing efficiency was first investigated. As
portrayed in Figure 3, this parameter is plotted versus the
geometry ratio for two different fluid velocities, Vh ) 1.3 10-3 m
s-1 and Vh ) 1.3 m s-1 which correspond to Reynolds numbers of
0.26 and 267, respectively. At the same time, the three linear
reference cases A, B, and C are simulated for the same Reynolds
numbers. Because of the constant Peclet assumption, it can be
noticed that the mixing efficiencies obtained for these three
straight geometries are independent of the flow rate. The results
obtained for references A and C illustrate the effect of decreasing
the channel width. Reducing the cross section or the transversal
diffusion length of 29% enhances the mixing efficiency of 95%. At
the same time, the difference observed between references B (L
) 2828 ím) and C (L ) 2000 ím) emphasizes the effect of
increasing the channel length or the residence time. For a length
increase of 29%, the relative mixing gain reaches only 13%.