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LBM Computational Simulation of Oscillations Caused by Formation and Detachment of Drops

Mardani, Ramin | 2017

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 50327 (45)
  4. University: Sharif University of Technology
  5. Department: Aerospace Engineering
  6. Advisor(s): Taeibi Rahni, Mohammad; Ebrahimi, Abbas
  7. Abstract:
  8. Formation and detachment of drops are of fundamental importance in studying two-phase flows, such as ink jet printing, emulsion, and spray. Drops are formed under the effects of surface tension forces. After formation, forces like gravity detach the drop from the rest of the fluid. The flow rate is varied from dripping to jetting regime. In this project, formation and detachment of drops were simulated, using LBM with phase field model, which can simulate flows with high-density ratios and is a robust method for applying wetting condition on the walls. Results were validated using single-phase and two-phase flows. After code validation, the oscillations caused by formation and detachment of drops from a nozzle under gravity effects were studied. Simulations in dripping to jetting regime show that most of these oscillations arise in dripping regime. Oscillations occur in horizontal and vertical directions and are visualized by vertical and horizontal displacements of drop. To survey different effects on this phenomenon, dimensionless numbers, such as Reynolds, Etvos and Ohnesorge were studied. Other parameters like viscosity ratio, wall thickness of nozzle, breakup length, and detachment time were also studied. The motion of drop under gravity condition and rising bubble was also simulated. In these cases, the effects of different dimensionless numbers, such as Ohnesorge and Etvos were studied. In these cases, we found that the oscillations of the pendant drop are caused by the existence of nozzle and uniform fluid flow
  9. Keywords:
  10. Lattice Boltzmann Method ; Multiphase Flow ; Oscillations ; Drop Detachment ; Droplet Formation

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