Vertical chaotic mixing of oscillating feedback micromixer in passive mode

Abstract

Oscillating feedback micromixers (OFMs) with short residence times enable efficient mixing in passive mode and have wide application potential. Chaotic mixing of the horizontal cross sections of OFMs has been proven, however, mixing performance of OFMs in the vertical direction has never been investigated. In this study, vertical chaotic advection in a three-dimensional (3D) OFM was demonstrated using Lagrange particle tracing approaches, including trajectory crossing mapping, simplified Poincaré mapping, and spacing change index. The results indicate that tracer particles released from any entry height can traverse the entire micromixer with the existence of vertical chaotic advection, and this chaotic advection promotes overall mixing. The vertical chaotic advection is generated by periodic transverse oscillation, with two vortices revolving in opposing directions. In addition, the species transport equation was simulated, indicating that efficient mixing can be performed at various heights along the entire vertical section, even near the top and bottom walls.