Numerical Simulation of Dry-Snow Avalanche Flow over Natural Terrain

Zwinger, Thomas; Kluwick, A.; Sampl, Peter

doi:10.1007/978-3-540-36565-5_5

Cited by 21 publications

(16 citation statements)

References 11 publications

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“…It is important to mention that in practical applications, the value of C DG is usually set to some numerical value that optimizes the fit between observations and numerical simulations (where C DG = 0.022 is used) [see, e.g., Zwinger et al , 2003]. However, here I propose that this drag coefficient be expressed explicitly in terms of essential physical parameters, for example, the volume fractions of the solid and fluid, the solid and fluid densities, terminal velocity of solid particles, particle diameter, and fluid viscosity.…”

Section: Model Derivationmentioning

confidence: 99%

A general two‐phase debris flow model

2012

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[1] This paper presents a new, generalized two-phase debris flow model that includes many essential physical phenomena. The model employs the Mohr-Coulomb plasticity for the solid stress, and the fluid stress is modeled as a solid-volume-fraction-gradient-enhanced non-Newtonian viscous stress. The generalized interfacial momentum transfer includes viscous drag, buoyancy, and virtual mass. A new, generalized drag force is proposed that covers both solid-like and fluid-like contributions, and can be applied to drag ranging from linear to quadratic. Strong coupling between the solid-and the fluid-momentum transfer leads to simultaneous deformation, mixing, and separation of the phases. Inclusion of the non-Newtonian viscous stresses is important in several aspects. The evolution, advection, and diffusion of the solid-volume fraction plays an important role. The model, which includes three innovative, fundamentally new, and dominant physical aspects (enhanced viscous stress, virtual mass, generalized drag) constitutes the most generalized two-phase flow model to date, and can reproduce results from most previous simple models that consider single-and two-phase avalanches and debris flows as special cases. Numerical results indicate that the model can adequately describe the complex dynamics of subaerial two-phase debris flows, particle-laden and dispersive flows, sediment transport, and submarine debris flows and associated phenomena.

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Section: Model Derivationmentioning

confidence: 99%

A general two‐phase debris flow model

2012

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“…The formation of further upper ash clouds from the surface of the dense basal flow can be incorporated into the model via shear, elutriation or an upward gas flux (Denlinger 1987;Takahashi & Tsujimoto 2000). This upward migration of particles could be incorporated via a negligibly thin re-suspension interface layer ( §1, Zwinger et al 2003). However, observations indicate that the interface is more probably a sharp transition than a transition zone ( §1), and that sedimentation dominates flow propagation.…”

Section: Discussionmentioning

confidence: 99%

A two-layer approach to modelling the transformation of dilute pyroclastic currents into dense pyroclastic flows

2010

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Most models of volcanic ash flows assume that the flow is either dilute or dense, with dynamics dominated by fluid turbulence or particle collisions, respectively. However, most naturally occurring flows feature both of these end members. To this end, a two-layer model for the formation of dense pyroclastic basal flows from dilute, collapsing volcanic eruption columns is presented. Depth-averaged, constant temperature, continuum conservation equations to describe the collapsing dilute current are derived. A dense basal flow is then considered to form at the base of this current owing to sedimentation of particles and is modelled as a granular avalanche of constant density. We present results which show that the two-layer model can predict much larger maximum runouts than would be expected from single-layer models, based on either dilute or dense conditions, as the dilute surge can outrun the dense granular flow, or vice versa, depending on conditions.

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“…Since the model is based on a one-dimensional avalanche model, it does not give an indication of the lateral extent of the hazard zones. For that purpose, the Austrian avalanche model SAMOS (SnowAvalancheMOdelling and Simulation; Zwinger and others, 2003) has been run for most of the investigated avalanche paths. The results of the risk model have then been adjusted according to the results of the SAMOS simulations.…”

Section: Application Of Risk Modelmentioning

confidence: 99%

Avalanche hazard zoning in Iceland based on individual risk

Arnalds¹,

Jónasson

Sigurðsson

2004

Ann. Glaciol.

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ABSTRACT. Avalanche hazard is a threat to many residential areas in Iceland. In 1995 two avalanche accidents, causing a total of 34 fatalities in areas thought to be safe, prompted research on avalanche hazard assessment. A new method was developed, and in 2000 a new regulation on avalanche hazard zoning was issued. The method and regulation are based on individual risk, or annual probability of death due to avalanches. The major components of the method are the estimation of avalanche frequency, run-out distribution and vulnerability. The frequency is estimated locally for each path under consideration, but the run-out distribution is based on data from many locations, employing the concept of transferring avalanches between slopes. Finally the vulnerability is estimated using data from the 1995 avalanches. Under the new regulation, new hazard maps have been prepared for six of the most vulnerable villages in Iceland. Hazard zones are delineated using risk levels of 0.2610^4, 0.7610^4 and 2610^4 a^1, with risk less than 0.2610^4 a^1 considered acceptable. When explaining the new zoning to the public, a measure of annual individual risk that allows comparison with other risks in society has proven advantageous.

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Numerical Simulation of Dry-Snow Avalanche Flow over Natural Terrain

Cited by 21 publications

References 11 publications

A general two‐phase debris flow model

A general two‐phase debris flow model

A two-layer approach to modelling the transformation of dilute pyroclastic currents into dense pyroclastic flows

Avalanche hazard zoning in Iceland based on individual risk

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