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Coalescence and migration of a droplet on a liquid pool with an inclined bottom wall

Pavan Kumar Kirar1, Pankaj S. Kolhe2, and Kirti Chandra Sahu1,*

  • 1Department of Chemical Engineering, Indian Institute of Technology Hyderabad, Sangareddy, 502 284, Telangana, India
  • 2Department of Mechanical and Aerospace Engineering, Indian Institute of Technology Hyderabad, Sangareddy, 502 284, Telangana, India

  • *ksahu@che.iith.ac.in
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Phys. Rev. Fluids 7, 094001 – Published 6 September, 2022

DOI: https://doi.org/10.1103/PhysRevFluids.7.094001

Abstract

We experimentally investigate the curvature-driven migration and coalescence of an ethanol droplet on the free surface of an ethanol pool with an inclined bottom wall by employing a high-speed shadowgraph technique. Two distinct coalescence phenomena, migrating partial coalescence and multidrop pinch-off, in addition to the normal partial coalescence and complete coalescence are observed when the Weber number (We), liquid depth at the impact point (dl/D), and inclination angle (θ) are varied. The three-phase contact line (TPCL) formed by the air-liquid interface on the inclined bottom wall and its curvature near the TPCL cause these unique dynamics. The coalescence behaviors are clearly demarcated by the regime maps drawn in dl/D−We and θ−dl/D spaces. We found that the transition between partial and complete coalescence occurs at We≈10, regardless of liquid depth, and that, for θ=18∘, the influence of the inclined wall is apparent for We>2, which increases as the inclination angle increases.

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Information

Phys. Rev. Fluids 7, 094001– Published 6 September, 2022
  • Received 9 May 2022
  • Accepted 25 August 2022
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