Experimental investigation of non-Newtonian droplet collisions

Experimental investigation of non-Newtonian droplet collisions: the role of extensional viscosity

Finotello, Giulia (Eindhoven University of Technology)
De, Shauvik (Eindhoven University of Technology)
Vrouwenvelder, Jeroen C.R. (Eindhoven University of Technology)
Padding, J.T. (TU Delft Intensified Reaction and Separation Systems)
Buist, Kay A. (Eindhoven University of Technology)
Jongsma, Alfred (Tetra Pak CPS)
Innings, Fredrik (Tetra Pak CPS)
Kuipers, J. A.M. (Eindhoven University of Technology)

2018

We investigate the collision behaviour of a shear thinning non-Newtonian fluid xanthan, by binary droplet collision experiments. Droplet collisions of non-Newtonian fluids are more complex than their Newtonian counterpart as the viscosity no longer remains constant during the collision process. Despite the complex collision dynamics, we are able to present a complete regime map based on non-dimensional Weber (We) number and impact parameter (B). We compare the collision outcomes of xanthan, glycerol and a milk concentrate at similar impact conditions. These experiments reveal very rich and complex collision morphologies for shear thinning xanthan solution, strikingly different from Newtonian droplet collisions. Unlike glycerol and milk, xanthan collisions show no reflexive separation even at very high We number. Instead of breakup, we observe disc-like shapes with an oscillating behaviour of the colliding droplets. A detailed analysis reveals that this outcome is related to increased viscous energy dissipation and extensional effects.

http://resolver.tudelft.nl/uuid:ca047929-7eeb-4014-80c9-607a84e7c56d

https://doi.org/10.1007/s00348-018-2568-2

0723-4864

Experiments in Fluids: experimental methods and their applications to fluid flow, 59 (7)

Institutional Repository

journal article

© 2018 Giulia Finotello, Shauvik De, Jeroen C.R. Vrouwenvelder, J.T. Padding, Kay A. Buist, Alfred Jongsma, Fredrik Innings, J. A.M. Kuipers