Effect of viscosity on droplet-droplet collisional interaction

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

doi:10.1063/1.4984081

Effect of viscosity on droplet-droplet collisional interaction

Journal article (2017)

Authors

Giulia Finotello Eindhoven University of Technology

J.T. Padding Intensified Reaction and Separation Systems - Mechanical, Maritime and Materials Engineering

Niels G. Deen Eindhoven University of Technology

Alfred Jongsma Tetra Pak CPS

Fredrik Innings Tetra Pak CPS

J.A.M. Kuipers Eindhoven University of Technology

Research Group

Intensified Reaction and Separation Systems (Mechanical, Maritime and Materials Engineering) (TU Delft)

DOI: https://doi.org/10.1063/1.4984081

Viscosity Surface tension Collision theories Drop coalescence Drop formation

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Published Date

2017

Language

English

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Faculty

Mechanical, Maritime and Materials Engineering

Department

Process and Energy

Research Group

Intensified Reaction and Separation Systems

Abstract

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.

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