First Advisor

Mark Weislogel

Term of Graduation

Fall 2021

Date of Publication

11-15-2021

Document Type

Dissertation

Degree Name

Doctor of Philosophy (Ph.D.) in Mechanical Engineering

Department

Mechanical and Materials Engineering

Language

English

Subjects

Drops, Viscosity, Contact angle, Reduced gravity environments, Fluid mechanics, Hydrophobic surfaces

DOI

10.15760/etd.7722

Physical Description

1 online resource (xiii, 108 pages)

Abstract

Enormous liquid puddles are observed to jump spontaneously from non-wetting substrates when exposed to the nearly step-reduction in body force common to drop tower test facilities. The phenomenon is similar to the second half of terrestrial drop bounce experiments except that (1) the initial static equilibrium configuration satisfies the static contact angle condition, (2) the initial height of the puddle is limited to the capillary height, and (3), for drop tower test durations on the order of seconds, puddle volumes can be over 104 times larger in mass (volume). The passive puddle jump mechanism provides a no-moving-parts deployment method for subsequent large drop dynamics investigations using drop towers. The effects of viscosity dampen large amplitude oscillations such that large spherical drops are quickly established from the initially flat viscous puddles. An experimental and numerical investigation of viscous puddle jump phenomena is pursued herein. A large drop tower data set is collected for puddle jump times, velocities, and character for viscosities 0.001 ≤ µ ≤ 1.18 kg/m·s, non-wetting contact angles 145º ≤ θ ≤ 160º, and puddle volumes 0.1 ≤ V ≤ 100 mL. We find that the jump time and velocity are weak and strong functions of viscosity, respectively. We benchmark the Gerris code for the contact line-driven flow and construct a combined experimental and numerical regime map for viscous puddle jump. We identify and distinguish the 'viscous jump' puddle volume limit, V ≈ (µ2/ρσ)3, below which puddles do not jump, but remain spherical wall-bound drops.

Rights

© 2021 Taif Hamed Saleh Al Juboori

In Copyright. URI: http://rightsstatements.org/vocab/InC/1.0/ This Item is protected by copyright and/or related rights. You are free to use this Item in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you need to obtain permission from the rights-holder(s).

Persistent Identifier

https://archives.pdx.edu/ds/psu/36913

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