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Numerical analysis of droplet motion over a flat plate due to surface acoustic waves

Sheikholeslam Noori, S. M ; Sharif University of Technology | 2020

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  1. Type of Document: Article
  2. DOI: 10.1007/s12217-020-09784-1
  3. Publisher: Springer , 2020
  4. Abstract:
  5. Micro-scale systems have gained considerable attention in recent years and a large amount of researches have been done in this field. In this study, the hydrodynamic interference of a droplet is comprehensively investigated under surface acoustic waves. This paper reveals the effects of some control parameters such as wave amplitude and wave frequency on the dynamical behavior of droplet. For these purposes, a two-dimensional multiple-relaxation-time color-gradient model lattice Boltzmann method is developed. This model is first validated by dynamical behaviors of a droplet subjected to shear flow. Moreover, displacement of a droplet affected by surface acoustic waves is comprehensively investigated. Our obtained simulations agree well with observations. According to our finding, the increase of frequency leads to the increment of required power to change the modes of the system from streaming to pumping or jetting states. Obtained results clearly show that hydrophobicity, reduction of viscosity, and increase of surface tension coefficient significantly influence on the flow control system and grow its sensitivity. Our results demonstrate that the minimum wave amplitude required to initiate pumping mode changes from 0.8 nm to about 1 nm when the frequency ranges are within 20 MHz to 200 MHz. The variations in jetting mode are also observed. Our findings clearly show that the minimum wave amplitude varies from about 2 nm to 4 nm when the frequency is changed from 20 MHz to 200 MHz. According to numerical analysis using lattice Boltzmann method, this work tried to capture the deformations of the fluid/fluid interface affected by surface acoustic waves and simulated the moving contact line in the high density ratio. These two main phenomena are recognized as significant parameter in our problem. © 2020, Springer Nature B.V
  6. Keywords:
  7. Flow control ; Lattice Boltzmann method ; Two-phase flow ; Acoustic surface wave devices ; Acoustic waves ; Drop formation ; Kinetic theory ; Motion analysis ; Numerical analysis ; Numerical methods ; Shear flow ; Acoustofluidics ; Dynamical behaviors ; Hydrodynamic interferences ; Moving contact lines ; Multiple-relaxation time ; Surface acoustic waves ; Surface tension coefficient ; Two phase flow
  8. Source: Microgravity Science and Technology ; Volume 32, Issue 4 , 2020 , Pages 647-660
  9. URL: https://link.springer.com/article/10.1007/s12217-020-09784-1