Date of Award:

8-2020

Document Type:

Thesis

Degree Name:

Master of Science (MS)

Department:

Mechanical and Aerospace Engineering

Committee

Tadd T. Truscott

Committee

Som Dutta

Committee

Hailei Wang

Abstract

When a stationary mass of water in a vertical tube is suddenly released, it creates a variety of artistic shapes and behaviors as it escapes the tube exit. As the descending water accelerates in the tube, friction along the tube wall slows the outer radius, resulting in a moving film entrained on the tube that trails the main body of water. When this film exits the tube, surface tension, gravity, and inertia interact to cause the film to create a wide variety of shapes, including jets, tubes, water bells, champagne glasses, and bubbles; rich forms that appear in other natural realizations of thin film dynamics. Despite the seeming simplicity and ubiquity of a water column exiting a vertical tube, this transient and beautiful phenomenon has never been described or studied. Here we show how and why the varied shapes trailing the column arise using both experimental data and theoretical modelling. We found that the forms observed are the result of a highly variable exiting film, which arises from the interaction of several distinct phenomena occurring inside the tube. These include the accelerating draining film and the development of waves on the film over time, both of which lead to a very variable exiting film. Theoretical predictions that are in agreement with experiments reveal how the ultimate shape, size and breakup point of the exiting film depend on the film thickness and velocity profile at the tube outlet. We anticipate that our research will provide a foundation for future studies involving the dynamics of falling water columns and films over a large range of physical scales and fluid properties. Furthermore, our results demonstrate how multiple known natural phenomena can interact unexpectedly to form artistically beautiful results. In this way, our work connects scientific and artistic fields, lending understanding to appreciate or create beautiful liquid shapes for fountains and other works of art.

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