faSavageHutterFOAM 1.0: depth-integrated simulation of dense snow avalanches on natural terrain with OpenFOAM

Abstract

Numerical models for dense snow avalanches have become central to hazard zone mapping and mitigation. Several commercial and free applications, which are used on a regular basis, implement such models. In this study we present a tool based on the open-source toolkit OpenFOAM ® as an alternative to the established solutions. The proposed tool implements a depth-integrated shallow flow model in accordance with current practice. The solver combines advantages of the extensive OpenFOAM infrastructure with popular models from the avalanche community. OpenFOAM allows assembling custom physical models with built-in primitives and implements the numerical solution at a high level.OpenFOAM supports an extendable solver structure, making the tool well-suited for future developments and rapid prototyping. We introduce the basic solver, implementing an incompressible, single-phase model for natural terrain, including entrainment. The respective workflow, consisting of meshing, pre-processing, numerical solution and postprocessing, is presented. We demonstrate data transfer from and to a geographic information system (GIS) to allow a simple application in practice. The tool chain is based entirely on open-source applications and libraries and can be easily customised and extended. Simulation results for a welldocumented avalanche event are presented and compared to previous numerical studies and historical data.

Constraints on Entrainment and Deposition Models in Avalanche Simulations from High-Resolution Radar Data

“…The normal vector field n b ∈ R 3 describes the surface and its curvature. The respective derivation can be found in Reference [33] and extensive explanations of the concept are given in Reference [32].…”

“…This can be attributed to the fact that the direction of velocity changes when following the surface and this term is best described as the force that is required to redirect the avalanche along the surface, that is, centrifugal force. For an extended explanation, the reader is referred to the Appendix A in Rauter et al [32]. The density ρ is a material parameter which we assume to be constant and the same for snow cover, flowing snow and deposition.…”

“…The numerical routine is based on the Finite Area Method which is implemented into OpenFOAM [39,40] and described in detail by Rauter and Tuković [33]. Further practical aspects, such as the interaction with GIS, are covered by Rauter et al [32].…”

“…In this work, we set up a benchmark, focusing on two remarkably different avalanches on the same day and in the same slope at Vallée de la Sionne. We investigate the above-mentioned comparison issues on the basis of the depth-integrated flow model faSavageHutterFoam implemented into the open-source Computational Fluid Dynamics software OpenFOAM [32]. The comparison between experiments and simulations is realized by using high resolution range-time data gathered with the GEODAR radar [29].…”

“…Experimental results are taken from Köhler et al [29]. Moreover, this work is intended to act as a validation of the model faSavageHutterFoam published by Rauter et al [32].…”