Articles | Volume 16, issue 11
Research article
03 Nov 2016
Research article |  | 03 Nov 2016

Snow avalanche friction relation based on extended kinetic theory

Matthias Rauter, Jan-Thomas Fischer, Wolfgang Fellin, and Andreas Kofler

Abstract. Rheological models for granular materials play an important role in the numerical simulation of dry dense snow avalanches. This article describes the application of a physically based model from the field of kinetic theory to snow avalanche simulations. The fundamental structure of the so-called extended kinetic theory is outlined and the decisive model behavior for avalanches is identified. A simplified relation, covering the basic features of the extended kinetic theory, is developed and implemented into an operational avalanche simulation software. To test the obtained friction relation, simulation results are compared to velocity and runout observations of avalanches, recorded from different field tests. As reference we utilize a classic phenomenological friction relation, which is commonly applied for hazard estimation. The quantitative comparison is based on the combination of normalized residuals of different observation variables in order to take into account the quality of the simulations in various regards. It is demonstrated that the extended kinetic theory provides a physically based explanation for the structure of phenomenological friction relations. The friction relation derived with the help of the extended kinetic theory shows advantages to the classic phenomenological friction, in particular when different events and various observation variables are investigated.

Short summary
Kinetic theory describes granular material under rapid motion. Macroscopic phenomena are determined by statistically describing collisions between particles. Recently, the theory has been extended to slow motion and quasi-static cases. Simplifications allow to apply this theory to snow avalanche simulations, where friction models with similar structure have been developed. Different test cases, comparing simulation and measurement data prove the applicability and highlight the improvements.
Final-revised paper