Deformation characteristics of droplet generated by Rayleigh jet breakup

Abstract

This article investigated the effects of driving and jet parameters on the deformation characteristics of the droplet generated by a Rayleigh jet breakup for the first time. The deformation characteristics of the droplet include its oscillation amplitude and oscillation period. The driving parameters are the dimensionless wavenumber and the initial amplitude of the perturbation. The jet parameters are non-dimensionalized as the Ohnesorge number. The non-dimensional Navier–Stokes equations were numerically solved to simulate the spatial instability of the jet breakup and obtain the complete oscillation process of the droplet. An equivalent oscillation amplitude was formulated based on the hydrodynamic similarity principle and energy method to explain the source of the oscillation of the droplet. The dependence of the oscillation amplitude was explained for the first time by analyzing the growth of the various harmonics of the perturbation derived from the Fourier expansion of axial velocity distribution. The results show that the higher harmonics caused by the non-linearity of the jet breakup have a certain influence on the dependence of the oscillation amplitude. The dependence of the oscillation period was formulated according to the linear solution of the problem of oscillating droplets.