Defense of Thesis Proposal: Xuan Wang

Wednesday, November 20, 2013, 10:00am-12:00pm

Cummings 202

“The Effects of Overburden and Temperature Gradients on Dry Snow Metamorphism”

Thesis Committee:
Ian Baker, Ph.D. (Chair)
Mary R. Albert, Ph.D.
Harold.J.Frost, Ph.D.
Zoe R. Courville, Ph.D.

Abstract: Typically, dry snow will metamorphose either towards a faceted granular structure under a temperature gradient or to rounded sintered ice grains under quasi-isothermal conditions. However, of the different types of metamorphism that may occur in snow layers, temperature gradient metamorphism (TGM) is perhaps the most significant one. Because of the formation of incohesive layers of depth hoar structures in snow packs during TGM, the strength of the snowpack along laterally extensive horizons will be reduced, which is, perhaps, the primary precursor to snow avalanche release. The relationship between snow microstructure and its mechanical properties is crucial for modeling the microstructural cause of snow avalanches. Therefore, the goal of this project is to explore the effects of temperature gradient and overburden on snow metamorphism, to understand the mass transfer mechanisms, and to develop a model for this behavior. Recently, scanning electron microscope (SEM) and micro-computed X-ray tomography (micro CT) have been used for studying snow metamorphism. In order to model the snow metamorphism under different situations (temperature gradient, uniaxial compressions, and alternating temperature gradient), cooling stage, compression stage, and two-side peltier stages will be used to complete in-situ observations. 3D images of snow specimens will then be loaded into COMSOLTM software to model the heat and mass transfer process. The relationship between the microstructural evolution and temperature distribution will be analyzed.

For more information, contact Daryl Laware at daryl.a.laware@dartmouth.edu.