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Capillary Filling in Open Rectangular Microchannels with a Spatially Varying Contact Angle
Li-Hsuan Chang1, Satish Kumar1
1Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota 55455, United States.
Langmuir : the ACS Journal of Surfaces and Colloids
|December 6, 2023
Summary
Researchers modified the Lucas-Washburn model to study capillary flow in open rectangular microchannels with varying contact angles. They found that specific contact angle variations can control fluid filling dynamics, offering design insights for microfluidic applications.
Area of Science:
- Physics
- Fluid Mechanics
- Materials Science
Background:
- Capillary flow in microchannels is crucial for microfluidics, heat exchangers, and printed electronics.
- Open rectangular microchannels offer accessible interiors, making them attractive for these technologies.
Purpose of the Study:
- To investigate the influence of spatially varying contact angles on capillary flow in open rectangular microchannels.
- To develop modifications of the Lucas-Washburn model for analyzing these complex flow scenarios.
Main Methods:
- Development of modified Lucas-Washburn models.
- Analysis of four distinct cases of contact angle variation: uniform differences, cross-sectional variation, monotonic length variation, and periodic length variation.
Main Results:
- Maximum filling velocity is more sensitive to wall contact angle variations.
- Cross-sectional contact angle variations can be averaged to simplify the model.
- Monotonic length variations alter the short-time meniscus position dynamics.
- Periodic contact angle variations are effectively described by an average uniform contact angle.
Conclusions:
- Spatially varying contact angles significantly influence capillary filling dynamics in microchannels.
- Understanding these variations allows for the design of controlled capillary filling.
- Naturally occurring contact angle variations can be accounted for in microchannel flow analysis.
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