A Mass Diffusion Model for Dry Snow Utilizing a Fabric Tensor to Characterize Anisotropy

作者：Shertzer, Richard H.^*; Adams, Edward E.

来源：Journal of Advances in Modeling Earth Systems, 2018, 10(3): 881-890.

DOI：10.1002/2017MS001046

• TEMPERATURE-GRADIENT METAMORPHISM
• GRANULAR-MATERIALS
• ELASTIC PROPERTIES
• HEAT
• HOMOGENIZATION
• CONDUCTIVITY
• COEFFICIENT
• TOMOGRAPHY
• SOLIDS
• RATES

A homogenization algorithm for randomly distributed microstructures is applied to develop a mass diffusion model for dry snow. Homogenization is a multiscale approach linking constituent behavior at the microscopic level-among ice and air-to the macroscopic material-snow. Principles of continuum mechanics at the microscopic scale describe water vapor diffusion across an ice grain's surface to the air-filled pore space. Volume averaging and a localization assumption scale up and down, respectively, between microscopic and macroscopic scales. The model yields a mass diffusivity expression at the macroscopic scale that is, in general, a second-order tensor parameterized by both bulk and microstructural variables. The model predicts a mass diffusivity of water vapor through snow that is less than that through air. Mass diffusivity is expected to decrease linearly with ice volume fraction. Potential anisotropy in snow's mass diffusivity is captured due to the tensor representation. The tensor is built from directional data assigned to specific, idealized microstructural features. Such anisotropy has been observed in the field and laboratories in snow morphologies of interest such as weak layers of depth hoar and near-surface facets.

• 出版日期2018-3