Rotation effect in split and recombination micromixing

This paper investigates the effect of rotation in split and recombination (SAR) mixing, one of the specific cases in which chaotic advection is applied to lamination, in a microchannel. Three types of SAR micromixers were designed: No-R, Co-R, and Count-R. They are defined by their rotation effect and by the direction of the rotation. The mixing efficiency for the rotation effect was compared at various flow rates between 1 mu l/min (Re 0.12) and 100 mu l/min (Re 12) in an experiment and between 100 mu l/min (Re 12) and 1000 mu l/min (Re 120) for numerical analysis. It is concluded that there are three regions, SAR dominant, mixed, and rotation dominant regions, following mixed regimes for the Reynolds number when rotation is applied to SAR. In the mixed region, the SAR is distorted by rotation and the efficiency rapidly decreases as the Reynolds number increases. In order to increase the mixing efficiency for a wide range of Reynolds numbers in a microchannel, the second region (mixed region) must be diminished by optimizing the intensity of the rotation. (C) 2007 Elsevier B.V. All rights reserved.