Thesis
Jet ejection following drop impact on micro-pillared hydrophilic substances
Washington State University
Master of Science (MS), Washington State University
05/2020
DOI:
https://doi.org/10.7273/000004117
Handle:
https://hdl.handle.net/2376/118633
Abstract
Droplet-wall interactions are well-known to generate a wide variety of outcomes such as spreading, splashing, receding, jetting, and rebounding. In this work, we focus on the evolution of jets that form during the recoil of impinging drops on partially wetting hydrophilic substrates composed of cylindrical micro-pillars. The impact of the millimeter-sized drops of water-glycerol mixtures on the micro-structured substrates is investigated by high-speed video photography. Impact velocity and fluid viscosity are varied to characterize the jets. Wetting angles are maintained between 43.6° ≤ [theta] ≤ 51.4°. 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 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 [PRL, 119(20), 2017] for jets induced by the capillary surface singularities. No jet is observed for sufficiently high drop viscosity. In this study, under varying We conditions, the maximum spreading factor (Dmax/Di) is measured. The data reveals a consistent dependence of Dmax/Di ~ We1/4, according to a recent theoretical model.
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Details
- Title
- Jet ejection following drop impact on micro-pillared hydrophilic substances
- Creators
- Anayet Ullah Siddique
- Contributors
- Hua Tan (Advisor) - Washington State University, Engineering and Computer Science (VANC), School of
- Awarding Institution
- Washington State University
- Academic Unit
- Engineering and Computer Science (VANC), School of
- Theses and Dissertations
- Master of Science (MS), Washington State University
- Publisher
- Washington State University
- Identifiers
- 99900890784801842
- Language
- English
- Resource Type
- Thesis