Effect of viscosity on droplet-droplet collisional interaction

Effect of viscosity on droplet-droplet collisional interaction

Finotello, Giulia (Eindhoven University of Technology)
Padding, J.T. (TU Delft Intensified Reaction and Separation Systems)
Deen, Niels G. (Eindhoven University of Technology)
Jongsma, Alfred (Tetra Pak CPS)
Innings, Fredrik (Tetra Pak CPS)
Kuipers, J.A.M. (Eindhoven University of Technology)

2017

A complete knowledge of the effect of droplet viscosity on droplet-droplet collision outcomes is essential for industrial processes such as spray drying. When droplets with dispersed solids are dried, the apparent viscosity of the dispersed phase increases by many orders of magnitude, which drastically changes the outcome of a droplet-droplet collision. However, the effect of viscosity on the droplet collision regime boundaries demarcating coalescence and reflexive and stretching separation is still not entirely understood and a general model for collision outcome boundaries is not available. In this work, the effect of viscosity on the droplet-droplet collision outcome is studied using direct numerical simulations employing the volume of fluid method. The role of viscous energy dissipation is analysed in collisions of droplets with different sizes and different physical properties. From the simulations results, a general phenomenological model depending on the capillary number (Ca, accounting for viscosity), the impact parameter (B), the Weber number (We), and the size ratio (Δ) is proposed.

Viscosity
Collision theories
Drop coalescence
Surface tension
Drop formation

http://resolver.tudelft.nl/uuid:1ce713a9-741b-4137-956b-c2ff4e8a396b

https://doi.org/10.1063/1.4984081

2018-06-06

1070-6631

Physics of Fluids, 29 (6)

Institutional Repository

journal article

© 2017 Giulia Finotello, J.T. Padding, Niels G. Deen, Alfred Jongsma, Fredrik Innings, J.A.M. Kuipers