Micro/Bio/Nanofluidics (Shen) Unit would like to invite you to the seminar by Prof. Zhenying Wang on January 11 (Thursday).
 
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Date:   January 11, 2024
Time:  15:00-16:00
Venue: C700, OIST
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Speaker:

Zhenying Wang
Assistant Professor
Department of Aeronautics and Astronautics
Kyushu University, Japan

Title:

Spreading Law of Evaporative Droplets

Abstract:

Droplet spreading is ubiquitous and plays a significant role in liquid-based energy systems, thermal management devices, and microfluidics. While the spreading of non-volatile droplets is well understood with quantitative descriptions, the spreading and flow transition in volatile droplets remains elusive due to the complexity added by interfacial phase change and non-equilibrium thermal transport. Here we show, using both mathematical modelling and experiments, that the wetting dynamics of volatile droplets can be scaled by the spatial-temporal interplay between capillary, evaporation, and thermal Marangoni effects. We quantify these complex interactions using phase diagrams based on detailed theoretical and experimental analyses. A spreading law of evaporative droplets is thereafter derived by generalizing Tanner’s law (valid for non-volatile liquids) to a full range of liquids with saturation vapor pressure spanning from 101 to 104 Pa and on substrates with thermal conductivity spanning from 10-1 to 103 W/m/K. Besides its importance in fluid-based industries, the conclusions also enable a unifying explanation to a series of individual works including the criterion of flow reversal and the state of dynamic wetting, making it possible to control liquid transport in diverse application scenarios.

Host:
Prof. Amy Shen