Rheologica Acta

, Volume 48, Issue 6, pp 611–624

Droplet formation in quickly stretched liquid filaments

Authors

    • Department of Mechanical and Industrial EngineeringUniversity of Toronto
  • Mohammad Pouran
    • Department of Mechanical and Industrial EngineeringUniversity of Toronto
    • Fluor Enterprises Inc.
Original Contribution

DOI: 10.1007/s00397-009-0356-x

Cite this article as:
James, D.F. & Pouran, M. Rheol Acta (2009) 48: 611. doi:10.1007/s00397-009-0356-x

Abstract

Film splitting necessarily occurs in roll coating and unwanted droplets can occur at high machine speeds when the resulting filaments break up. To study this ‘misting’ problem, an apparatus was designed and built to simulate filament fluid mechanics. The device creates a filament by elongating a liquid bridge and stretches the filament at a high and constant rate of acceleration to mimic coating machine kinematics. Filament breakup was observed using a high-speed video camera and the images were analyzed to yield droplet size and number. With Newtonian fluids, a single droplet formed at Ohnesorge (Oh) numbers less than 0.1 and more and smaller droplets were produced at Oh numbers above 0.1. Associative polymer solutions, prepared as weakly elastic fluids to represent industrial coatings, produced even more and smaller droplets, but only for Ohnesorge numbers in the range of 0.01 to 0.1.

Keywords

Filament breakupQuick stretchingMistingDropletsElasticityUniaxial extension

Copyright information

© Springer-Verlag 2009