Jet ejection following drop impact on micropillared hydrophilic substrates

Anayet Ullah Siddique, Marcus Trimble, Feng Zhao, Mark M. Weislogel, and Hua Tan
Phys. Rev. Fluids 5, 063606 – Published 15 June 2020

Abstract

Droplet-wall interactions are well known to generate a wide variety of outcomes such as spreading, splashing, receding, jetting, and rebounding. In this paper, we focus on the evolution of jets that form during the recoil of impinging drops on partially wetting hydrophilic substrates composed of cylindrical micropillars. The impact of the millimeter-sized drops of water-glycerol mixtures on the microstructured hydrophilic substrates is investigated by high-speed video photography. Impact velocity and fluid viscosity are varied to characterize the jets. Wetting angles are maintained in the range of 43.6θ51.4. A regime map is constructed to convey the jet behavior at a glance. We find that jet speed, height, and diameter scale linearly with the Weber number. We also find that the jet originates from the inertial collapse of an air cavity formed during the recoil phase of the drop following impact on the microstructured substrate. The relationship between the size of the top jet drop and jet velocity obeys the scaling law of [Gañán-Calvo, Phys. Rev. Lett. 119, 204502 (2017)] for jets induced by capillary surface singularities. No jet is observed for sufficiently high drop viscosity.

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  • Received 8 January 2020
  • Accepted 27 May 2020

DOI:https://doi.org/10.1103/PhysRevFluids.5.063606

©2020 American Physical Society

Physics Subject Headings (PhySH)

  1. Research Areas
  1. Physical Systems
Fluid Dynamics

Authors & Affiliations

Anayet Ullah Siddique1, Marcus Trimble1, Feng Zhao1, Mark M. Weislogel2, and Hua Tan1,*

  • 1School of Engineering and Computer Science, Washington State University-Vancouver, 14204 NE Salmon Creek Avenue, Vancouver, Washington 98686, USA
  • 2Department of Mechanical & Materials Engineering, Portland State University, 1930 SW 4th Avenue, Portland, Oregon 97201, USA

  • *Corresponding author: hua.tan@wsu.edu

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Vol. 5, Iss. 6 — June 2020

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