Vibration-induced drop atomization and bursting

Abstract

A liquid drop placed on a vibrating diaphragm will burst into a fine spray of smaller secondary droplets if it is driven at the proper frequency and amplitude. The process begins when capillary waves appear on the free surface of the drop and then grow in amplitude and complexity as the acceleration amplitude of the diaphragm is slowly increased from zero. When the acceleration of the diaphragm rises above a well-defined critical value, small secondary droplets begin to be ejected from the free-surface wave crests. Then, quite suddenly, the entire volume of the drop is ejected from the vibrating diaphragm in the form of a spray. This event is the result of an interaction between the fluid dynamical process of droplet ejection and the vibrational dynamics of the diaphragm. During droplet ejection, the effective mass of the drop–diaphragm system decreases and the resonance frequency of the system increases. If the initial forcing frequency is above the resonance frequency of the system, droplet ejection causes the system to move closer to resonance, which in turn causes more vigorous vibration and faster droplet ejection. This ultimately leads to drop bursting. In this paper, the basic phenomenon of vibration-induced drop atomization and drop bursting will be introduced, demonstrated, and characterized. Experimental results and a simple mathematical model of the process will be presented and used to explain the basic physics of the system.

Footprint geometry and sessile drop resonance

“…For both, typical observables are mode shapes [11,[14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32], resonance frequencies [11,[14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32], and the evolution of surface waves with forcing amplitude [18,23,[29][30][31][33][34][35]. The free surface waves oscillate at the forcing frequency (harmonically) when the forcing acceleration is low.…”

Generation and development of surface waves on the interface boundary of viscous fluid oscillating drop

“…Current numerical works studying the droplet dynamics on vibrating surfaces are very few [8,10]. The work [10] numerically studies the oscillation and spraying process of a single liquid droplet from the solid rod.…”

“…The work [10] numerically studies the oscillation and spraying process of a single liquid droplet from the solid rod. In this study the physical problem statement has several rather strong assumptions: the initial droplet configuration was defined as half sphere, in addition to this the possible movement of a contact line was not considered; in hydrodynamic equations, cycling acceleration of a substrate is added to the gravity acceleration.…”

“…In this study the physical problem statement has several rather strong assumptions: the initial droplet configuration was defined as half sphere, in addition to this the possible movement of a contact line was not considered; in hydrodynamic equations, cycling acceleration of a substrate is added to the gravity acceleration. Also the work [10] describes only solutions for the two dimensional problem.…”

Surface waves on a semitoroidal water ring

“…Hence, for simplicity, we assume that the base state is close to a semi-circle with constant radius R. Small fluctuations of the surface can then be expressed as R+ζ(θ), where ζ(θ) is a small radial displacement deviating from R. This assumption leads to a simple linear analysis for the perturbed fluid surface. A fully nonlinear, numerical treatment of the 6 oscillations and Faraday instabilities of a driven viscous drop has been considered by James et al [27].…”