EGU24-14924, updated on 09 Mar 2024
EGU General Assembly 2024
© Author(s) 2024. This work is distributed under
the Creative Commons Attribution 4.0 License.

Comparative Analysis of Geophysical Flow Models: Voellmy, μ(I), and μ(R) Rheologies 

Yu Zhuang1, Brian McArdell2, and Perry Bartelt1
Yu Zhuang et al.
  • 1WSL Institute for Snow and Avalanche Research SLF, Davos, Switzerland
  • 2Swiss Federal Institute for Forest, Snow and Landscape Research WSL, Birmensdorf, Switzerland

The experimental-based μ(I) rheology is now prevalent to describe the movement of gravitational mass flows. Though the μ(I) rheology has been successfully applied to the modelling of historical debris flows and rock avalanches, its physical implication is not fully understood. In this study, we re-formulate the μ(I) rheology as a Voellmy-type relationship, which is composed of a Coulomb friction term and a turbulent term. We find that different from the classic Voellmy rheology (ξ is a constant), the turbulent coefficient ξ in the μ(I) rheology is heavily dependent on the avalanche height and velocity, indicating the shear-thinning features. However, as μ(I) rheology is a pure function of velocity (for a constant height), the friction exhibits no change during the acceleration and deceleration stage. With this purpose, we introduce a newly proposed μ(R) rheology that relates the friction to the production and decay of fluctuation energy (granular temperature) R. Using one-dimensional block models, we show the equivalence of I and R, and elucidate why similar results of μ(I) and μ(R) rheologies are easily obtained. Ultimately, this comparative analysis offers valuable insights into improving geophysical flow models, enhancing our understanding of flow behavior's dependence on various factors and leading to more accurate assessments and mitigation of geophysical hazards.

How to cite: Zhuang, Y., McArdell, B., and Bartelt, P.: Comparative Analysis of Geophysical Flow Models: Voellmy, μ(I), and μ(R) Rheologies , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14924,, 2024.