Fundamental study of microvortices evolution in square microcavities using microfluidics

Significance 

Recent technological advances in various research fields like biology and fluid mechanics require efficient and effective microfluidic devices. These applications require precise and accurate control of the flow of fluid in the microfluidic devices which has led to the development of diverse devices configurations. To this note, many researchers have been motivated to thoroughly investigate the transport and flow behaviors in microfluidic devices and particularly microcavities characterized by microvortices. Consequently, understanding the effect of the geometric factors on the flow behaviors in microcavities is equally important. This is because microcavities are used to control the formation of microvortices, which is the operating principle of numerous microfluidic devices. Thus, optimizing microcavity configuration for better use of microvortices for a different application requires though investigation on the effect of inlet Reynolds number and the microcavities geometry on the fluid flow behaviors.

A group of researchers at Beijing University of Technology, Professor Feng Shen, Dr. Min Xu, Dr. Zheng Wang, and Professor Zhaomiao Liu in collaboration with Professor Bin Zhou at Weifang University investigated the effects of geometry factors on microvortices evolution in square microcavities. Their research work is currently published in the research journal, Microfluidics and Nanofluidics.

The research team used micro-particle image velocimetry (micro-PIV) and numerical simulation to investigate the flow behaviors in different square microcavities at a wider range of Reynolds numbers. Also, they investigated the influence of the hydraulic diameter of the main microchannel, the inlet Reynolds number and the microcavity sizes on the microvortices evolution in different square microcavities. This made it easy to determine the critical Reynold numbers for the appearance of microvortices and transformation of flow patterns. Eventually, the simulation and experimental results were compared.

The authors observed that the flow behaviors and microvortices morphology were generally determined by the microcavity wall confined effect and the shear stress effect. However, at the same Reynolds number, the mentioned two effects varied for different square microcavities. Additionally, the flow characteristics depended on the actual sizes of the microcavities and the main microchannel width. Furthermore, the critical Reynolds number for the transformation of the different flow patterns at each microcavity exhibited a linear relationship with the sizes of the microcavities. This resulted in an increase in the size of the microcavity thus also increasing the critical Reynolds number. The agreement between the simulation results and the experimental results confirmed the accuracy of the experiment.

The geometrical factors comprised of the main microchannel width and the actual size of the microcavity that significantly influenced the transport and flow behaviors of microcavities characterized with microvortices. According to the authors, the results presented in this study provides a useful guideline for better optimization of microcavity configuration for controlling the formation of microvortices. As such, it will lead to effective design, optimization, and application of the microcavity-featured microfluidic devices.

microvortices evolution in square microcavities using microfluidics, Advances in Engineering
Microvortices evolution in confined square microcavities with different sizes at Reynolds number of 200.

 

About the author

Feng Shen is an associate professor in College of Mechanical Engineering and Applied Electronics Technology, Beijing University of Technology (BJUT, China). He received his PhD degree in Fluid Mechanics from Institute of Mechanics, Chinese Academy of Sciences (CAS) in 2009.

Research interests:
– microfluidics
– lab-on-a-chip
– experimental fluid mechanics
– hemodynamics

E-mail:[email protected]

About the author

Min Xu received his Master degree from the Beijing University of Technology (BJUT, China) in 2018 under the supervision of Professor Feng Shen. He is currently pursuing his Ph.D. in the Beijing University of Technology.

Research interests:
– microfluidics
– experimental fluid mechanics
– particle sorting in microcavities

E-mail:[email protected]

About the author

Zheng Wang received his Master’s degree from the Beijing University of Technology (BJUT, China) in 2017 under the supervision of Professor Feng Shen.

Research interests:
– microfluidics
– experimental fluid mechanics
– microcavity flow

E-mail:[email protected]

About the author

Zhaomiao Liu is a professor in College of Mechanical Engineering and Applied Electronics Technology, Beijing University of Technology (BJUT, China). She received her PhD degree in Applied Mechanics from Beijing Institute of Technology (BIT) in 1998.

Research interests:
– microfluidics
– hemodynamics
– computational fluid dynamics
– fluid-structure interaction
– its engineering applications

E-mail:[email protected]

About the author

Bin Zhou is an assistant professor in School of Civil Engineering and Architecture, Weifang University (China). He received his Bachelor’s degree in engineering mechanics at Tongji University (China) and PhD degree in fluid mechanics from Institute of Mechanics, Chinese Academy of Sciences (CAS). He joined Weifang University in 2011.

Research interests:
– microgravity fluid mechanics
– thermal and micro fluid measurements
– fluid flow simulation
– steel structures
– green buildings

E-mail:[email protected]

Reference

Shen, F., Xu, M., Zhou, B., Wang, Z., & Liu, Z. (2018). Effects of geometry factors on microvortices evolution in confined square microcavities.  Microfluidics and Nanofluidics, 22(4). .

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