Ice Flow Over a Bump: Experiment and Numerical Simulations

Abstract

AbstractThe flow of ice over a bump under steady-state conditions has been studied both experimentally and numerically. The experiments were performed with the ice viscometer installed at the Laboratoire de Glaciologie et Géophysique de l'Environnement du C.N.R.S. (LGGE) in Grenoble, France. The flow was observed by means of a marker network photographed at fixed time intervals. The separation of the ice down-stream of the bump and the non-linearity of the generally accepted Glen’s flow law led to the modelling of this flow using a finite-element method. The results describe the velocity and stress fields in ice moving over a bump and obeying Glen’s flow law (until now only relatively rough approximations of these fields have been given in the literature). The comparison of the observed and calculated network deformations shows that, although ice flowing over a bump does not undergo steady creep, the use of Glen’s flow law with an exponent n = 3 remains justified when simulating the flow of a glacier over its bed under steady-state conditions.