Recalculation of an artificially released avalanche with SAMOS and validation with measurements from a pulsed Doppler radar

A joint experiment was carried out on 10 February 1999 by the Swiss Federal Institute for Snow and Avalanche Research (SFISAR) and the Austrian Institute for Avalanche and Torrent Research (AIATR, of the Federal Office and Re-search Centre for Forests, BFW) to measure forces and velocities at the full scale experimental site CRÊTA BESSE in VALLÉE DE LA SIONNE, Canton du Valais, Switzerland. A huge avalanche could be released artificially, which permitted extensive investigations (dynamic measurements, im-provement of measurement systems, simulation model verification, design of protective measures, etc.). The results of the velocity measurements from the dual frequency pulsed Doppler avalanche radar of the AIATR and the recalculation with the numerical simulation model SAMOS are explained in this paper

Current Status of the AVL Avalanche Simulation Model - Numerical Simulation of Dry Snow Avalanches

This paper gives a short summary of the underlying physics, mathematical formulation and numerical treatment of a snow avalanche model developed at AVL, Graz, in co-operation with the Federal Service for Avalanche and Torrent control of Austria. A dense flow-and an aerosol part of the avalanche are distinguished. For each part a separate model has been established. The application of these models and the comparison of the results with observations are described as well as the intended coupling and further development of the models. / Cet article présente de façon succincte les fondements physiques, la formulation systématique et le traitement numérique d'un modèle d'avalanche développé par AVL, à Graz, en coopération avec le Service Fédéral Autrichien de Protection contre les Avalanches et les Torrents. Les parties dense et aérosol de l'écoulement de l'avalanche sont traitées de façon distincte. Pour chacune, un modèle spécifique a été développé. L'application de ces modèles et la comparaison des résultats avec des observations sont décrits ainsi que le couplage projeté et le développement futur des modèles

Simulation of powder avalanches by FIRE ; Verification of results on example of Wolfsgruben avalanche (march 1988) in St Anton Tyrol Austria

The application of the AVL-powder-avalanche model, the comparison between the results of this numerical model an the mapped damages are demonstrated to the Wolfsgruben avalanche disaster in St. Anton (March 1988) in Tyrol/Austria. / L'application du modèle AVL d'avalanche poudreuse et la comparaison entre les résultats obtenus par ce modèle numérique et les dégâts cartographiés sont présentés dans le cas particulier de l'accident de l'avalanche de Wolfsgruben, à Saint Anton dans le Tyrol, en Autriche

Interaction entre digues et avalanches poudreuses : détermination des lois de frottement pour les équations de Saint-Venant

International audienceOne of the goals of the European project CADZIE was the determination of simple friction laws for shallow water avalanche models in order to describe the interaction between defense structures and powder as well as dense avalanches. In this paper, we will focus on powder avalanches. We carried out physical model experiments in a water tank, in which the powder snow was simulated by a "heavy" salt solution. Respecting both the densimetric Froude number and the density ratio to meet the laws of similarity required a prohibitively large tank. Practically, a distortion of the density ratio must be accepted. A ratio of 1.2 can be achieved in the water tank with salt suspensions, whereas powder avalanches attain ratios of the order of 10. Quasi-two and three-dimensional experiments with several configurations of dams were conducted in the water tank and the internal velocity of the flow was measured using Doppler ultrasonic velocimetry. Numerical simulations of such experiments were done using a turbulent "heavy gas" model: two mass balances, one for mixture and one for the salt solution are considered, but only one momentum balance for the entire mixture implying that both water and salt solution are assumed to move with the same velocity. The obtained results were compared with measurements obtained in the water tank and the effect of density ratio was numerically studied. As it was shown that the entrainment of air is modified by the density ratio, friction coefficients were determined for different density ratio (2.5 and 10) and for different values of dam's height (from 0.2 to 0.6 H0, where H0 is the height of the reference avalanche). The practical use of such coefficient tables is shown

The Juno Waves Investigation

International audienc

An Equivalence Relation for Local Path Sets

Abstract We propose a novel enhancement to the task of collision-testing a set of local paths. Our approach circumvents expensive collision-tests, yet it declares a continuum of paths collision-free by exploiting both the structure of paths and the outcome of previous tests. We define a homotopy-like equivalence relation among local paths and provide algorithms to (1) classify paths based on equivalence, and (2) implicitly collision-test up to 90 % of them. We then prove both correctness and completeness of these algorithms before providing experimental results showing a performance increase up to 300%.