Drop deformation and breakup in flows with shear

• Droplet breakup is studied in flows with shear by means of the VOF method.
• A regime of bag, shear and intermediate breakup modes is considered.
• The larger the shear rate, the more the deformed drop tilts.
• Breakup approaches shear breakup as the Reynolds nr. and shear rate are increased.
• An empirical model for breakup time is suggested for spray simulation applications.

A Volume of Fluid (VOF) method is applied to study the deformation and breakup of a single liquid drop in shear flows superimposed on uniform flow. The effect of shearing on the breakup mechanism is investigated as a function of the shear rate. Sequential images are compared for the parameter range studied; density ratios of liquid to gas of 20, 40, and 80, viscosity ratios in the range 0.5–50, Reynolds numbers between 20, a constant Weber number of 20, and the non-dimensional shear rate of the flow G=0–2.1875G=0–2.1875. It is found that while shear breakup remains similar for all values of shear rate considered, other breakup modes observed for uniform flows are remarkably modified with increasing shear rate. The time required for breakup is significantly decreased in strong shear flows. A simple model predicting the breakup time as a function of the shear rate and the breakup time observed in uniform flows is suggested.