Loading...

Numerical Analysis of Drop Motion over a Flat Solid Surface Due to Surface Acoustic Waves, Using Lattice Boltzmann Method

Sheikholeslam Noori, Mahdi | 2020

588 Viewed
  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 52799 (45)
  4. University: Sharif University of Technology
  5. Department: Aerospace Engineering
  6. Advisor(s): Mohammad Taiebi Rahni; Shams Taleghani, Arash
  7. Abstract:
  8. In recent years, there have been a tremendous research performed in the field of sestems containing small scales. However, besides all advantages of such systems, microfluidic systems have extraordinary difficulties and pumping liquid drops as part of some of these systems has been very important issue. An approach related to flow control is use of surface acoustic waves (SAW), which is known as acoustofluidic device. So far, most researches have only qualitatively investigated acoustic flux phenomenon. On the other hand, computational research is ongoing more emphasizing on accuracy, optimization, and obtaining more detailed physical understanding of SAW applications. Investigation of the hydrodynamics of a drop located on a surface under influence of SAW is the main subject of this dissertation. Computational simulation of acoustofluidic phenomenon, using lattice Boltzmann method (LBM), presenting acoustic applications in flow control, and a relatively complete parametric study are the main objectives of this work. Numerical developments for applying the acoustic force, using geometrical wetting boundary condition in high density ratios, studing the hysteresis of contact angle, and vision of recognizing more physical details of the problem are the main innovations of this study. We have used a multi-relaxation time (MRT) color-gradient LBM for this interfacial multiphase flow problem. The results show relatively close agreements with previous analytical and experimental data. Considering contact angle hysteresis, our results show about 20% more accurate, while the difference with experimental data is about 0.8%. In addition, the limits for appearance of acoustofluidic phenomenon for an ideal surface was obtained. It was observed that if the SAWʼs amplitude for moving a drop must be increased about 1.2 times. While, for the onset of above phenomenon, frequency needs to be approximately doubled. Also, the results show that, for the hydrophobic surfaces, the drop moves about 203 times faster. The dynamical behavior of contact angle was also investigated for the first time in this dissertation. Finally, using SAW actuators as flow control in two fields, namely: fast separation of drops from surfaces and overcoming gravity effects were studied and reported in this work
  9. Keywords:
  10. Surface Acoustic Waves (SAW) Resonator ; Two Phase Flow ; Flow Control ; Lattice Boltzmann Method ; Contact Angle ; Acoustofluidics ; Geometrical Wetting Boundary Conditions

 Digital Object List

 Bookmark

No TOC