A NEW APPROACH FOR COMPLETE MIXING BY TRANSVERSE AND STREAMWISE FLOW MOTIONS IN MICRO-CHANNELS

Mixing control is an important issue in micro-fluid chip applications, such as μTAS (Micro-Total Analysis System) or LOC (Lab-on-Chip) because the flow at micro-scale is highly laminar. Several flow control schemes had been developed for complete mixing in the micro-channels in the past decades. However, most of the mixing control schemes are performed by utilizing specific excitation devices, such as electrokinetic, magnetic or pressure drivers. This paper investigates a new control scheme which is composed of a series of flow manipulation by changing the pressure at the two inlets of the micromixer as the external excitation. The fluids from two inlets are introduced to a square mixing chamber, which provides a space where the streamwise and transverse flow motions take place. The results show that the micromixer can be used to produce a large recirculation zone with series of small transverse fringes under external excitations. It is found that this new flow pattern enhances mixing processes at the micro-scale. A complete mixing can be achieved under appropriate flow control with the corresponding design.