MS Thesis Defense: Anthony Cheng

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"The Horizontal Infiltration of Water through Porous Snow via Gravity Current"

Abstract

Few studies have combined the thermodynamics and fluid mechanics of how water horizontally infiltrates porous ice. It is important to understand this infiltration process since water populating the pore space of ice directly impacts the density, porosity, and wetness of ice. These properties influence the mechanics and tensile strength of ice, as greater amounts of infiltration result in faster or more widespread deformation events. In this study, we devise a one-dimensional depth-integrated model for water horizontally infiltrating porous ice via gravity current as a Darcy flow from a source of constant depth. We first analyze the infiltration process in the absence of phase change and find that the source-driven infiltration behaves self-similarly. We then capture the infiltration process subject to freezing with an analytical relationship between the source porosity and the time over which the pores at the source are frozen shut. Once the source is frozen shut, residual infiltration in the snowpack as a wetting front becomes weaker and a freezing front develops from the source. Under these freezing dynamics, we bound the region of liquid water by using the similarity solution to locate the wetting front and approximate the freezing front evolution. We then discuss methods to validate and apply the model through experiments and field observations. We construct a regime diagram to predict breakthrough potential given snowpack dimensions, ice temperature scale, and initial source porosity. We also discuss methods to extend the model theoretically to icy satellites and warm water sources.

Thesis Committee

• Professor Colin Meyer (advisor)
• Professor Kasia Warburton (U Cambridge)
• Professor Laura Ray
• Professor Don Perovich

Contact

For more information, contact Thayer Registrar at thayer.registrar@dartmouth.edu.