A Parametric Study of the Coalescence of Liquid Drops in a Viscous Gas

Abstract

The coalescence of two liquid drops surrounded by a viscous gas is considered in the framework of the conventional model. The problem is solved numerically with particular attention to resolving the very initial stage of the process which only recently has become accessible both experimentally and computationally. A systematic study of the parameter space of practical interest allows the influence of the governing parameters in the system to be identified and the role of viscous gas to be determined. In particular, it is shown that the viscosity of the gas suppresses the formation of toroidal bubble predicted in some cases by early computations where the gas' dynamics was neglected. Focussing computations on the very initial stages of coalescence and considering the large parameter space allows us to examine the accuracy and limits of applicability of various `scaling laws' proposed for different `regimes' and, in doing so, reveal certain inconsistencies in recent works. A comparison to experimental data shows that the conventional model is able to reproduce many qualitative features of the initial stages of coalescence, such as a collapse of calculations onto a `master curve' but, quantitatively, overpredicts the observed speed of coalescence and there are no free parameters to improve the fit. Finally, a phase diagram of parameter space, differing from previously published ones, is used to illustrate the key findings.

arXiv commentAccepted for publication in the Journal of Fluid Mechanics

References in corpus (12)

• Coalescence of Liquid Drops
• Inviscid coalescence of drops
• Coalescence of bubbles and drops in an outer fluid
• Viscous to Inertial Crossover in Liquid Drop Coalescence
• The inexorable resistance of inertia determines the initial regime of drop coalescence
• Short time dynamics of viscous drop spreading
• Coalescence of Liquid Drops: Different Models Versus Experiment
• Approach and Coalescence of Liquid Drops in Air
• The Dynamics of Liquid Drops and their Interaction with Solids of Varying Wettabilites
• Finite Element Simulation of Dynamic Wetting Flows as an Interface Formation Process
• The Dynamics of Liquid Drops Coalescing in the Inertial Regime
• The Coalescence of Liquid Drops in a Viscous Fluid: Interface Formation Model

Cited by in corpus (8)

• Capillary Breakup of a Liquid Bridge: Identifying Regimes and Transitions
• Air Entrainment in Dynamic Wetting: Knudsen Effects and the Influence of Ambient Air Pressure
• Wetting boundary conditions for multicomponent pseudopotential lattice Boltzmann
• The Coalescence of Liquid Drops in a Viscous Fluid: Interface Formation Model
• Dynamics of viscous coalescing droplets in a saturated vapor phase
• The Formation of a Bubble from a Submerged Orifice
• Coalescence of immersed droplets on a substrate
• When elasticity affects drop coalescence