Snow avalanche friction relation based on extended kinetic theory

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

doi:10.5194/nhess-16-2325-2016

Cited by 13 publications

(20 citation statements)

References 93 publications

(143 reference statements)

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“…In terms of rheology, we follow the assumption of rough surfaces and consequently shear-dominated deformation in the whole fluid domain. This approach has proven to be useful considering real scale avalanches [19,21]. Moreover, it leads to a very simple implementation of rheology since lateral deviatoric stress can be neglected in shear-dominated flows (e.g., [22,18]).…”

Section: Introductionmentioning

confidence: 99%

A finite area scheme for shallow granular flows on three-dimensional surfaces

Rauter

Tuković

2018

Computers & Fluids

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Shallow flow or thin liquid film models are used for a wide range of physical and engineering problems. They are applicable to free surface flows, when the flow thickness is distinctly smaller than the lateral dimension. Respective situations exist in automotive and aircraft engineering (soiling, icing, exterior water management), industrial processes (coating, fire suppression), environmental flows (river and lake hydrodynamics, atmospheric flows), and natural hazards (floods, avalanches, debris flow). Shallow flow models allow capturing the free surface of the fluid with little effort and reducing the three-dimensional problem to a quasi two-dimensional problem through depth-integrating the flow fields. Despite remarkable progress of such models in the last decade, accurate description of complex topography remains a challenge. Interaction with topography is particularly critical for granular flows, because their rheology requires modeling of the pressure field, which is strongly linked to surface curvature and associated centrifugal forces. Shallow granular flow models are usually set up in surface-aligned curvilinear coordinates, and velocity is represented as a two-dimensional surfacealigned vector field. The transformation from Cartesian to curvilinear coordinates introduces fictitious forces, however, which result in complex governing equations. In this paper, we set up the shallow flow model in three-dimensional Cartesian coordinates and preserve three-dimensional velocity in the depthintegrated model. Topography is taken into account with a constraint on velocity. This approach is commonly applied by the thin liquid film community. The advantage is a curvature-free mathematical description that is convenient for complex topographies. The constraint on velocity yields a solution for the pressure field, which is required for the pressure-dependent rheology of granular materials. The model is therefore well-suited for granular flows on three-dimensional terrain, e.g., avalanches. The mathematical model is solved with a second-order accurate, implicit finite area scheme, based on the open source software OpenFOAM. We conduct numerical simulations for various cases to verify the numerical routine based on comparisons with analytical results and a grid refinement study. We establish connections to former solutions and discuss advantages and drawbacks of the proposed method from both mechanical and numerical perspectives.

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Section: Introductionmentioning

confidence: 99%

A finite area scheme for shallow granular flows on three-dimensional surfaces

Rauter

Tuković

2018

Computers & Fluids

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“…Finally, we evaluate OpenFOAM simulations with regard to convergence during mesh refinement to give a quantitative estimation of numerical uncertainties as recommended by Roache (1997). The numerical solution should converge to the unknown analytical solution with increasing grid resolution, and the numerical uncertainty should decay with the order of the applied method.…”

Section: Simulation Evaluationmentioning

confidence: 99%

“…8 for the OpenFOAM solver. Respective mean cell sizes, an estimation of the numerical uncertainty following Roache (1997) and execution times (excluding time for mesh generation, which may take several minutes) are presented in Table 1. Here, the runout is defined as the length of the central avalanche path (see Fig.…”

Section: Case Studymentioning

confidence: 99%

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

et al. 2018

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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.

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“…However, radar data are not straightforward to interpret and not easily applicable for parameter optimization. Previous studies compare depth-averaged velocities from simulations with peak intensity velocities from Doppler radar measurements [30,31], although they might actually not be comparable.…”

Section: Introductionmentioning

confidence: 99%

“…This work builds on the basic flow model of Rauter and Tuković [33] and the rheological model from Rauter et al [31]. Experimental results are taken from Köhler et al [29].…”

Section: Introductionmentioning

confidence: 99%

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

Rauter

Köhler

2019

Geosciences

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Depth-integrated simulations of snow avalanches have become a central part of risk analysis and mitigation. However, the common practice of applying different model parameters to mimic different avalanches is unsatisfying. In here, we analyse this issue in terms of two differently sized avalanches from the full-scale avalanche test-site Vallée de la Sionne, Switzerland. We perform depth-integrated simulations with the toolkit OpenFOAM, simulating both events with the same set of model parameters. Simulation results are validated with high-resolution position data from the GEODAR radar. Rather than conducting extensive post-processing to match radar data to the output of the simulations, we generate synthetic flow signatures inside the flow model. The synthetic radar data can be directly compared with the GEODAR measurements. The comparison reveals weaknesses of the model, generally at the tail and specifically by overestimating the runout of the smaller event. Both issues are addressed by explicitly considering deposition processes in the depth-integrated model. The new deposition model significantly improves the simulation of the small avalanche, making it starve in the steep middle part of the slope. Furthermore, the deposition model enables more accurate simulations of deposition patterns and volumes and the simulation of avalanche series that are influenced by previous deposits.

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Snow avalanche friction relation based on extended kinetic theory

Cited by 13 publications

References 93 publications

A finite area scheme for shallow granular flows on three-dimensional surfaces

A finite area scheme for shallow granular flows on three-dimensional surfaces

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

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

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