Micro-fluid mixing is an important aspect of many of the various micro-fluidic systems used in biochemical production, biomedical industries, microenergy systems and some electronic devices. Active or highly effective passive mixing techniques are often required. In this study, two pulsed injectors are used to actively enhance mixing in a high aspect ratio microchannel (125 μm deep and 1 mm wide). The main channel has two adjacent flowing streams with 100% dye and 0% dye concentrations, respectively. Two injectors (125 μm deep and 250 μm wide) are located on opposite sides of the channel and off-set in the downstream direction. A dye solution is used to map local mixing throughout the channel by measuring concentration variations as a function of both space and time. Images of the concentration variations within the channel are used to quantify mixing. It is shown that there is a high degree of repeatability of concentration distribution as a function of phase of the pulsing cycle. The flow rate ratio between the injectors and main channel is found to be the most influential parameter on overall mixing, and evidence of an optimal flow rate ratio and frequency is presented. A nondimensional correlation is presented that could be used to predict the level of mixing for the conditions studied.

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