Scenarios of droplet deformation and breakup

Authors: Kékesi, T.K., Amberg, G.A., Prahl Wittberg, L.
Document Type: Conference
Pubstate: Published
Journal: 8th International Conference on Multiphase Flow (ICMF), Jeju, Korea (2013)
Year: 2013


Deformation and breakup of a single stationary spherical droplet induced by steady disturbances is examined in the bag- and shear breakup regimes. This numerical study applies a Volume of Fluid (VOF) method to the flow solver in order to resolve the droplet phase. Steady droplet deformation in flows with low inertia-, as well as the parameters influencing the breakup are investigated. Different flow conditions and material properties are considered. For the steady droplet deformation, Weber numbers (We) of 0.1, 1, 5, and 10 at a Reynolds number (Re) of 100, and density- and viscosity ratios of the liquid and the gas corresponding to 80 and 55.6 respectively, are investigated. For the parameter study considering breakup, a Weber number of 20, Reynolds numbers of 20, 50, 80, 100, and 200, density ratios of 40 and 80, and viscosity ratios of 5, 20, 35, and 50 are applied. Results show good agreement with observations of earlier studies for Weber numbers below 12, i.e. the onset of breakup. As the Weber number becomes greater than 12, with the viscosity- and density ratios investigated here, surface tension loses its dominance and the drop experiences shear- and bag breakup for most cases. Interesting intermediate regimes are revealed, where breakup is a combination of the above two modes. By relating the competing shear and inertial forces it is possible to estimate the characteristic times of each breakup type. Thus, in this work, we propose a criterion for the transition between the two modes in terms of material properties and the Reynolds number, for which a regime map is obtained.