A Computational Study of Mixing Microchannel Flows

Motivated by recent experimental advances (Stroock et al. 2002) in microfluidic mixers, we study the passive mixing and flow properties of a patterned microchannel by means of computational fluid dynamics (CFD). Such geometries overcome the low Reynolds number, high Peclet number boundaries to efficient mixing by creating a three-dimensional flow that yields chaotic trajectories for advected passive scalars. The flow seems to exploit an effective shearing mechanism, or 'ditch mixing,' rather than the alternating span-wise vorticity mechanism we anticipated. Further, we find superexponential mixing for a modification of the geometry. It is hoped that such CFD studies advance both the capabilities and the understanding of such micropatterned mixing flows.