Convex Grooves in Staggered Herringbone Mixer Improve Mixing Efficiency of Laminar Flow in Microchannel.
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.
Mechanical Engineering Department, University of Wisconsin-Milwaukee, Milwaukee, WI, United States of America.
Tae Joon
http://orcid.org/0000-0003-1669-1996
TJ
Kwak
Mechanical Engineering Department, University of Wisconsin-Milwaukee, Milwaukee, WI, United States of America.
Young Gyu
YG
Nam
Industrial Engineering Department, University of Wisconsin-Milwaukee, Milwaukee, WI, United States of America.
Maria Alejandra
MA
Najera
Department of Biomedical Engineering, Yonsei University, Wonju, Republic of Korea.
Sang Woo
SW
Lee
Great Lakes Water Institute, University of Wisconsin-Milwaukee, Milwaukee, WI, United States of America.
J Rudi
JR
Strickler
Mechanical Engineering Department, University of Wisconsin-Milwaukee, Milwaukee, WI, United States of America.|Great Lakes Water Institute, University of Wisconsin-Milwaukee, Milwaukee, WI, United States of America.
Woo-Jin
WJ
Chang
D003198:Computer Simulation; D004867:Equipment Design / Q000379:methods; D046210:Microfluidic Analytical Techniques / Q000379:methods*; D044085:Microfluidics / Q000379:methods*