On the Influence of Droplet Size on the Breakup Induction Period in the Flow behind a Shock Wave

Abstract

In this paper, we computationally study the influence of the initial diameter of a water droplet on the dynamics and breakup induction period in the flow behind a passing shock wave. For this purpose, a series of calculations were performed for a fixed Weber number \( \mathrm {We} = 400 \) and a variable initial diameter \( d = 1.4, 2.8, 5.6 \) mm of the water droplet. The numerical technique is based on the VOF method, the LES model is used to take into account turbulence, and the technology of adapted dynamic grids is used to describe the behavior of the interfacial boundary at main turbulent scales; this has made it possible to resolve secondary water droplets up to 20 \( \mu \)m in size. The droplet shape, the flow structure near and in the droplet wake, and the nature of mass entrainment were investigated. As a result of the calculations, the dependences of the breakup time on the dimensionless droplet diameter were obtained, the breakup induction time was determined, and the time constant of droplet interaction with the flow was calculated to estimate the droplet breakup lag.