Continuum-mechanical, Anisotropic Flow model for polar ice masses, based on an anisotropic Flow Enhancement factor

TL;DR

This paper introduces the CAFFE model, a comprehensive continuum-mechanical framework for polar ice masses that accounts for anisotropic flow behavior based on grain orientation distribution and fabric evolution.

Contribution

It presents a novel anisotropic flow law for ice, incorporating fabric evolution and anisotropic enhancement factors within a continuum-mechanical model.

Findings

The CAFFE model accurately describes anisotropic ice flow.

The flow law remains anisotropic despite collinearity of tensors.

Fabric evolution is governed by four distinct physical effects.

Abstract

A complete theoretical presentation of the Continuum-mechanical, Anisotropic Flow model, based on an anisotropic Flow Enhancement factor (CAFFE model) is given. The CAFFE model is an application of the theory of mixtures with continuous diversity for the case of large polar ice masses in which induced anisotropy occurs. The anisotropic response of the polycrystalline ice is described by a generalization of Glen's flow law, based on a scalar anisotropic enhancement factor. The enhancement factor depends on the orientation mass density, which is closely related to the orientation distribution function and describes the distribution of grain orientations (fabric). Fabric evolution is governed by the orientation mass balance, which depends on four distinct effects, interpreted as local rigid body rotation, grain rotation, rotation recrystallization (polygonization) and grain boundary migration (migration recrystallization), respectively. It is proven that the flow law of the CAFFE model is truly anisotropic despite the collinearity between the stress deviator and stretching tensors.