Abstract
The liquid streams in a microchannel are hardly mixed to form laminar flow, and the mixing issue is well described by a low Reynolds number scheme. The staggered herringbone mixer (SHM) using repeated patterns of grooves in the microchannel have been proved to be an efficient passive micro-mixer. However, only a negative pattern of the staggered herringbone mixer has been used so far after it was first suggested, to the best of our knowledge. In this study, the mixing efficiencies from negative and positive staggered herringbone mixer patterns as well as from opposite flow directions were tested to investigate the effect of the micro-structure geometry on the surrounding laminar flow. The positive herringbone pattern showed better mixing efficiency than the conventionally used negative pattern. Also, generally used forward flow gives better mixing efficiency than reverse flow. The mixing was completed after two cycles of staggered herringbone mixer with both forward and reverse flow in a positive pattern. The traditional negative pattern showed complete mixing after four and five cycles in forward and reverse flow direction, respectively. The mixing effect in all geometries was numerically simulated, and the results confirmed more efficient mixing in the positive pattern than the negative. The results can further enable the design of a more efficient microfluidic mixer, as well as in depth understanding of the phenomena of positive and negative patterns existing in nature with regards to the surrounding fluids.
Highlights
Microfluidic devices are defined as devices in which at least one of the dimensions is less than a millimeter
The laminar flow is explained by a low Reynolds number that is conventionally less than one in a microfluidic device [3]
The effect of staggered herringbone mixer (SHM) geometries on the mixing of two liquids was investigated by experiments as well as numerical studies
Summary
Microfluidic devices are defined as devices in which at least one of the dimensions is less than a millimeter. Major applications of microfluidic devices are manipulation and detection of chemicals and biological molecules such as DNA, proteins, and cells, related to food, health,[1] drug. Convex Grooves in SHM Improve Mixing Efficiency of Laminar Flow in Microchannel screenings, etc.[2] In this micro-scale analytical device, mixing is one of the most important properties to improve its performance, due to the creation of laminar flow, which has high momentum diffusion and low momentum convection. The laminar flow is explained by a low Reynolds number that is conventionally less than one in a microfluidic device [3]. Mixing is difficult to achieve in a microfluidic channel; various micromixers have been developed [4,5]
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