Abstract
A novel design for vortex modulation of a passive micromixer, named as the circulation-disturbance micromixer (CDM), has been achieved and analyzed experimentally and numerically. The micromixer consists of slanted grooves on the bottom and a zigzag barrier on the top. In this micromixer, the fluid produces a transverse motion perpendicular to the main field, and two modulated and hyperbolic vortices of disparate size are induced. The active-like agitation produced by the constructive interference of these two vortices induces increased flow through the grooves and the mixing efficiency is hence improved significantly. The 3D flow structure in CDM has been analyzed through both numerical simulation (CFD-ACE+) and two methods of visualization - using dyes and using micro laser-induced fluorescence (μ-LIF, B-phycoerythrin (BPE) and Allophycocyanin alpha subunit (ApcA)) with a confocal microscope. Our results contribute to an understanding of the resulting enhanced hyperbolic flow mixing and provide also a superior microfluidic element for a 'lab on a chip'. Compared with a slanted groove micromixer, the mixing index of the designed CDM-2T increases 132%, whereas CDM-4T and CDM-8T respectively increase 183% and 280% at Reynolds number 10. © 2007 IOP Publishing Ltd.