Journal ArticleDOI
Micro-PIV investigation of the internal flow transitions inside droplets traveling in a rectangular microchannel
TLDR
In this paper, the internal flow field of droplets traveling in a rectangular microchannel by means of microparticle image velocimetry is studied. And the effects of capillary number, viscosity ratio and interfacial tension on the flow topology are investigated.Abstract:
This paper discusses the studies on the internal flow field of droplets traveling in a rectangular microchannel by means of microparticle image velocimetry, specifically concentrating on the effects of capillary number, viscosity ratio and interfacial tension. The flow topology is predominantly dependent on the capillary number. It shows that the evident transitions from three pairs of recirculation zones at lower capillary numbers to one pair of recirculation zones near the sidewalls with low velocity in the central area at intermediate capillary numbers, then to a pair of recirculation zones closest to the axial centerline with high velocity in the central area at higher capillary numbers. There are two critical capillary numbers increasing with viscosity ratio in the evolution of flow features. Droplet size only influences two velocity components values other than the flow topology within intervals separated by the critical values. The equilibrium mechanism of viscous friction force and Marangoni stress dominate the internal topological transition in a surfactant added system. The obtained internal fluid phenomena inside droplets are beneficial to provide a guideline for screening of biochemical reaction conditions in the device.read more
Citations
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Journal ArticleDOI
Two-phase flow and mass transfer in microchannels: A review from local mechanism to global models
Chaoqun Yao,Yuchao Zhao,Haiyun Ma,Haiyun Ma,Yanyan Liu,Yanyan Liu,Qiankun Zhao,Qiankun Zhao,Guangwen Chen +8 more
TL;DR: In this article, the authors present a review of the recent progress on flow and mass transfer of two-phase systems in microchannels, in a multi-scale view from local mechanism to global behavior.
Journal ArticleDOI
New insights into the pressure during the merged droplet formation in the squeezing time
Wenbo Han,Xueye Chen +1 more
TL;DR: In this paper, a three-dimensional numerical simulation of the merged droplet formation (MDF) in the double T-junction microchannel was performed to investigate the effects of the flow rate of the continuous phase, continuous viscosity and the interfacial tension on the pressure by the level-set method.
Journal ArticleDOI
Velocity distributions in trapped and mobilized non-wetting phase ganglia in porous media
TL;DR: Micro-particle tracking velocimetry in a micro-fluidic model is used in order to visualise the velocity distributions inside the trapped phase globules prior and during mobilisation, and time-averaged and instantaneous velocity vectors have been determined using fluorescent microscopy.
Journal ArticleDOI
Breakup dynamics of droplets in an asymmetric bifurcation by μPIV and theoretical investigations
Wang Xiang,Zhaomiao Liu,Yan Pang +2 more
TL;DR: In this article, the mass conservation law was used to predict the geometric shape of droplets in an asymmetric bifurcation and the critical neck thickness that determines whether a droplet will break after flowing through the split.
Journal ArticleDOI
Internal flow patterns of a droplet pinned to the hydrophobic surfaces of a confined microchannel using micro-PIV and VOF simulations
Guang Yang,Guang Yang,Alexandros Terzis,I. Zarikos,S. Majid Hassanizadeh,Bernhard Weigand,Rainer Helmig +6 more
TL;DR: In this paper, both experimental results and numerical simulations of a droplet pinned to the hydrophobic surfaces of a confined microfluidic channel, as a result of contact angle hysteresis, are presented.
References
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