For Re ) 267 (curve B), the mixing efficiency first greatly
increases up to 98.6% for a geometry ratio increasing up to 4. For
s/w > 4, the efficiency slightly decreases down to 88.1% illustrating
the existence of an optimal zigzag geometry. However, the mixing
efficiency values obtained for s/w > 2 are larger than the
asymptotic one corresponding to reference B. Because the
diffusion conditions remain similar in this study (Pe ) 2600),
results obtained for higher Reynolds number highlight that themixing efficiency is strongly dependent on the convection regime.
This mixing efficiency can be significantly improved, taking
advantage of the laminar recirculation induced by the zigzag
angles at high flow rates.