Table of Contents
Journal of Fluids
Volume 2015 (2015), Article ID 405696, 15 pages
Research Article

Separation Criteria for Off-Axis Binary Drop Collisions

1United Technologies Research Center, 411 Silver Lane, MS 129-19, East Hartford, CT 06108, USA
2Department of Mechanical and Industrial Engineering, University of Toronto, Toronto, ON, Canada M5S 3G8

Received 15 December 2014; Accepted 14 April 2015

Academic Editor: Robert Spall

Copyright © 2015 Mary D. Saroka and Nasser Ashgriz. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Off-axis collisions of two equal size droplets are investigated numerically. Various governing processes in such collisions are discussed. Several commonly used theoretical models that predict the onset of separation after collision are evaluated based on the processes observed numerically. A separation criterion based on droplet deformation is found. The numerical results are used to assess the validity of some commonly used phenomenological models for drop separation after collision. Also, a critical Weber number for the droplet separation after grazing collision is reported. The effect of Reynolds number is investigated and regions of permanent coalescence and separation are plotted in a Weber-Reynolds number plane for high impact parameter collisions.