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Electrowetting of power-law fluids in microgrooved channels

Izadi, R ; Sharif University of Technology | 2020

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  1. Type of Document: Article
  2. DOI: 10.1063/5.0010819
  3. Publisher: American Institute of Physics Inc , 2020
  4. Abstract:
  5. Studying the dynamic behavior of droplets is of great importance in the electrowetting phenomena. However, despite the widespread use of non-Newtonian fluids in industry and daily life including medicine, food, petroleum, environmental biomass, and lab on a chip, most studies have focused on Newtonian fluids. In this study, a power-law fluid is considered as a typical example of non-Newtonian fluids and its dynamic behavior is investigated within a microchannel, and the results are compared with those of the Newtonian fluids. Both the grooved and non-grooved substrates are considered. For this purpose, the governing equations for the two phase fluid flow are solved using the finite element method, and the phase field method is used for interface tracking. We show that for four types of the considered grooves in the microchannel, different changes in the fluid dynamics are observed. When the droplets pass over the grooves, the velocity decreases and the pressure drop increases. These behaviors are intensified when the size of the grooves increases. In the shear thinning fluids, the velocity reduction is larger and even causes the drop to stop. However, in the shear thickening fluids, the velocity reduction is smaller, and the droplets can cross the grooves. After the grooves, the velocity of the droplets increases suddenly. Finally, it is shown that the time of separation of a droplet in the splitting process completely depends on the fluid type, which is much less in the shear thinning fluids compared to the shear thickening types. © 2020 Author(s)
  6. Keywords:
  7. Drops ; Flow measurement ; Microchannels ; Non Newtonian liquids ; Phase transitions ; Rheology ; Shear flow ; Shear thinning ; Two phase flow ; Velocity ; Viscous flow ; Wetting ; Governing equations ; Interface tracking ; Non Newtonian fluids ; Phase field methods ; Shear thickening fluid ; Shear thinning fluids ; Splitting process ; Two phase fluid flow ; Non Newtonian flow
  8. Source: Physics of Fluids ; Volume 32, Issue 7 , July , 2020
  9. URL: https://aip.scitation.org/doi/abs/10.1063/5.0010819