Numerical and Theoretical Investigation of Effect of Density Ratio on the Critical Weber Number of Droplet Breakup

Abstract

The critical Weber number is necessary for estimating droplet sizes and interfacial area in numerical computations of multiphase, multi-fluid and chemical reactive flows. The density ratio of droplet to continuous fluid is one of the important parameters to affect the critical Weber number of droplet breakup under an impulsive acceleration. The effect of density ratio on the critical Weber number is numerically and theoretically investigated in this paper by the Moving Particle Semi-implicit method and the linear analyses of the Kelvi-Helmholtz and Rayleigh-Taylor instabilities. Both results show that the critical Weber number is inversely proportional to density ratio; specifically, the critical Weber number is strongly dominated by density ratio when it is less than 3, but weakly decreased as density ratio is greater than 3. The breakup Weber number at the onset of droplet breakup is also obtained from the numerical results. It is almost constant and close to 0.4 for the range of density ratio between 1 and 9.