The coalescence to stretching separation transition in binary droplet collisions

ORAL

Abstract

The transition from coalescence to stretching separation occurs in binary droplet collisions as the collision off-set (impact parameter) is increased. This work investigates the impact of fluid viscosity on this transition for equi-diameter droplets It shows that the transition is viscosity-independent for Ohnesorge numbers spanning an order of magnitude. The maximum length of coalesced droplet ligand formed prior to stretching separation is 3.35 droplet diameters. Surprisingly this was constant for all conditions tested, i.e. independent of Weber and Ohnesorge number. This observation can be used to develop a simple, robust model of the coalescence-stretching separation transition.

*This work was supported by the EPSRC project ‘Evaporative Drying of Droplets and theFormation of Micro-structured and Functional Particles and Films’ (grant no. EP/N025245/1), a Royal SocietyEnhancement Award (grant no. RGF\EA\181002), the University of Leeds and the EPSRC Centre for DoctoralTraining in Fluid Dynamics at the University of Leeds (grant no. EP/L01615X/1)

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Publication: J. Fluid Mech. (2021), vol. 927, A9, doi:10.1017/jfm.2021.674

Presenters

  • Andrew E Bayly

    • Univ of Leeds

Authors

  • Andrew E Bayly

    • Univ of Leeds

  • Karrar Al-Dirawi

    • University of Leeds

  • Thomas C Sykes

    • University of Oxford

  • Khaled H Al-Ghaithi

    • University of Leeds

  • Jose Rafael Castrejon-Pita

    • Queen Mary Univ London
    • Department of Mechanical Engineering, University College London
    • University College London