Rayleigh-Taylor Instability Induced Liquid Atomization

Abstract

The destabilization of a two-fluid interface is of interest in various applications ranging from spray formation to ocean-wave currents. In most practical spray systems, instabilities that occur on the interface lead to form fragments. Among such instabilities, those caused due to the radial motion of the interface in a cylindrical configuration (Rayleigh-Taylor) are of current interest. We study the instability characteristics of a cylindrical bubble surrounded by an infinite medium of liquid. Linear stability analysis is used as a tool to understand the mechanics. A general dispersion relation has been derived for an inviscid, immiscible and incompressible pair of fluids. This dispersion relation is used to predict the most unstable wavenumber as well as the dominant instability growth rate. It was found that the Bond number is a primary determinant of the most unstable wavenumbers, dominant instability growth rate as well as the neutral stability points. Surprisingly, it was also found out that radial velocity alone (in the absence of radial acceleration) is sufficient to destabilize a cylindrical interface, unlike in the case of either planar or spherical polar configurations.