Item: Scaled laboratory experiments on the evolution of fluidised avalanches.
-
-
Title: Scaled laboratory experiments on the evolution of fluidised avalanches.
Proceedings: International Snow Science Workshop, Davos 2009, Proceedings
Authors: J. Koegl1,2 , A. Graf1 , L. Rammer2 , K. Kleemayr1 , M.A. Kern1 , P. Gauer1 , G. Kapeller2 and M. Aufleger2 1Federal Research and Training Centre for Forests, Natural Hazards and Landscapes (BFW), Innsbruck, Austria 2Unit of Hydraulic Engineering
Date: 2009
Abstract: Scaled chute experiments with avalanche-like flows of dry granular matter have proven to be a useful tool for the design of technical avalanche protection measures. However, the characteristics of the generated model avalanches have been restricted to the dense flow state so far. We use a 8 m long and 1 m wide laboratory chute with variable inclination to generate avalanche-like flows that exhibit typical avalanche features such as a rotational head, fingering of the front and a distinct fluidised suspension layer: by careful choice of model materials and boundary conditions, we have been able to access flow states where air drag plays a significant role. The model avalanches are characterised in terms of flow height, basal flow velocity and by the 2D velocity field derived from a PIV analysis of high-speed camera recordings of the flow through a transparent side-wall of the chute. Furthermore, we characterise the model flows by dimensionless quantities such as Froude-, Stokes- and Reynolds numbers. The results indicate that the values of some of the dimensionless characteristics of the model avalanches match those of real-scale powder avalanches. High-speed video recordings of the impact of the model avalanches on a scaled snow net demonstrate that the snow net holds back a significant part of the avalanche mass and that the flow state of the mass penetrating and overrunning the snow net undergoes a transition from super- to subcritical flow behaviour.
Presenters: Unknown
Keywords: scaled avalanche experiments, snow net, breaking obstacle
Subjects: scaled laboratory experiments evolution of fluidised avalanches snow net
-
Digital Abstract Not Available
-