Numerical investigations on the deformation and breakup of an n-decane droplet induced by a shock wave

Abstract

This paper adopts the coupled level-set and volume-of-fluid and the large eddy simulation methods to simulate the deformation and breakup of an n-decane droplet under the action of a shock wave. We aim to investigate the effects of the shock Mach number and droplet diameter on temporary deformation and breakup characteristics at high Weber numbers from 5813 to 22 380. Additionally, special attention is paid to subsequent sub-droplet size distributions, which many researchers generally ignore. The results indicate that the evolution of droplet deformation and breakup in the shear breakup regime generally agrees with the obtained experimental data. Based on the present methods, the physical mechanisms for variations of multiple recirculation zones and the development of Kelvin–Helmholtz instability in wave formation are discussed. Larger shock Mach number and smaller droplet diameter can significantly increase the cross-stream and stream-wise deformations. Moreover, both relaxation and breakup times are directly proportional to the initial droplet diameters but inversely proportional to the shock Mach numbers. Eventually, as the shock Mach number increases, the superficial area and mass ratios of sub-droplets to parent droplets all increase from 5.596 to 8.278 and from 23.38% to 38.38%, while the ratios increase from 2.652 to 18.523 and from 4.63% to 92.7%, respectively, as the droplet diameter decreases.