Master's Theses

Date of Award

2012

Document Type

Thesis

Department

Mechanical Engineering

Keywords

Coalescence, Fluid Dynamics, Diffuse into face model

Abstract

"A numerical study has been performed using a lattice Boltzmann method (LBM) for an incompressible binary fluid based on the Cahn-Hilliard diffuse interface approach to investigate the early-time coalescence dynamics of two liquid drops. The two drops approach each other at a very low Weber number (We) and the coalescence process is driven by surface tension. When the two drops come into contact, the curvature diverges and causes infinitely large surface tension forces, leading to the formation of a rapidly growing liquid bridge. Depending on the forces that govern the widening of the liquid bridge, the coalescence dynamics can be classified into viscous regime, where the viscous forces govern the coalescence and inertial regime, where the inertial forces govern the coalescence. For the coalescence in the inertial regime, where the liquid bridge radius r grows as r(t) ∝ √t, the effect of the initial separation between the drops on the growth-rate of the liquid bridge radius is examined for two different initial configurations. The first configuration has the two drops initially connected by a small finite radius of the liquid bridge, and the second one has the two drops initially separated by a small finite distance. The effect of changing the Weber number on the time evolution of the liquid bridge is also examined to see at what value of We the approaching velocity effect should be taken into account." between the drops on the growth-rate of the liquid bridge radius is examined for two different initial configurations. The first configuration has the two drops initially connected by a small finite radius of the liquid bridge, and the second one has the two drops initially separated by a small finite distance. The effect of changing the Weber number on the time evolution of the liquid bridge is also examined to see at what value of We the approaching velocity effect should be taken into account."

 
 

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