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Computational Simulation of High Density Ratio Drop Deformation and Breakup, Using Lattice Boltzmann Method

Kiani, Mehran | 2015

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 47635 (45)
  4. University: Sharif University of Technology
  5. Department: Aerospace Engineering
  6. Advisor(s): Taeibi Rahni, Mohammad; Karbaschi, Mohsen
  7. Abstract:
  8. Deformation and breakup of drops are the basisof many interfacial flow studies and appear in a number of industrial applications, e.g., spray painting, spray combustion, emulsion, foam, sedimentation, and rain. Following their formation, drops may enter a region where hydrodynamicforces are large enough to cause their significant deformation and breakup. When a drop breaks apart into a multitude of small fragments due to disruptive hydrodynamicforces, the process is termed secondary atomization or breakup. Due to many engineering and scientific applications of multiphase and multi-component flows, they have been the main topic of many researchers for many years. Particularly, interfacial flows, wherein the main concern is the interface between a liquid and a fluid (liquid-fluid interface) have been receiving much attention, especially because of modern advancements in related experimental and computational hardwares and softwares.
    Fortunately, in about the last one and a half decades, lattice Boltzmann method (LBM) has shown to be one of the most popular and applied numerical methods in interfacial flows. However, an important existing challenge in LBM is when dealing with high density ratio interfacial problems, wherein it is usually very difficult to achieve a stable numerical scheme with minimum amount of numerical diffusion. Thusfar, many researchers have tried to overcome this deficiency. Also, in this research, a new free energy based LBM model for simulation of interfacial flows with density ratios of up to about 1,000 and dynamic viscosity ratios of up to about 100 is proposed. Also, in the free energy constants estimation process, a new parameter is introduced, whose values are found numerically as a function of interface thickness (W). In order to validate our new model, four well-known classical problems (Laplace law, time evolution of a rectangular drop to a circular one, capillary wave, and phase separation) have been computationally simulated. In this model, the spurious currents are in the order of 10-8
  9. Keywords:
  10. Lattice Boltzmann Method ; Drop Deformation ; Drop Breakage ; Large Density Ratio ; Interfacial Flows ; Hydrodynamic Effects

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