CFD Simulation and Analysis of Emulsion Droplet Formation from Straight-Through Microchannels
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- 作者：Isao Kobayashi ; Sukekuni Mukataka ; and Mitsutoshi Nakajima
- 刊名：Langmuir
- 出版年：2004
- 出版时间：October 26, 2004
- 年：2004
- 卷：20
- 期：22
- 页码：9868 - 9877
- 全文大小：870K
- 年卷期：v.20,no.22(October 26, 2004)
- ISSN：1520-5827
文摘
We recently proposed a technique for preparing monodisperse emulsions with a coefficient of variationbelow 5% from a silicon array of micrometer-sized channels perpendicular to the plate surface, named astraight-through microchannel (MC). This study involved three-dimensional computational fluid dynamics(CFD) simulations to calculate the formation of an oil-in-water (O/W) emulsion droplet from straight-through MCs with circular and elliptic cross sections. The CFD results demonstrated that the oil phasethat passed through the elliptic MCs exceeding a threshold aspect ratio between 3 and 3.5 was cut offspontaneously into a small droplet with a diameter of ~40 
m. Sufficient space for water at the channelexit had to be maintained for successful droplet formation. The formation and shrinkage of a neck insidethe channel caused an increased pressure difference inside the channel and an increased velocity valuenear the neck. The pressure and velocity values at the neck drastically changed, and the neck was cut offinstantaneously just before the completion of droplet formation. This process was triggered by a graduallyincreased pressure difference between the circular neck and inflating oil phase. The findings obtained inthis paper provide useful numerical and visual information about the droplet formation phenomena fromthe straight-through MCs. The CFD results were verified by the experimental results, showing that theCFD approach can help design a suitable channel structure.
m. Sufficient space for water at the channelexit had to be maintained for successful droplet formation. The formation and shrinkage of a neck insidethe channel caused an increased pressure difference inside the channel and an increased velocity valuenear the neck. The pressure and velocity values at the neck drastically changed, and the neck was cut offinstantaneously just before the completion of droplet formation. This process was triggered by a graduallyincreased pressure difference between the circular neck and inflating oil phase. The findings obtained inthis paper provide useful numerical and visual information about the droplet formation phenomena fromthe straight-through MCs. The CFD results were verified by the experimental results, showing that theCFD approach can help design a suitable channel structure.