scholarly journals Numerical simulation of drifting snow: erosion and deposition models

1998 ◽  
Vol 26 ◽  
pp. 191-196 ◽  
Author(s):  
Mohamed Naaim ◽  
Florence Naaim-Bouvet ◽  
Hugo Martinez
Keyword(s):  
Mass Exchange ◽  
Field Measurements ◽  
Numerical Results ◽  
Back Reaction ◽  
Erosion And Deposition ◽  
Deposition Model ◽  
Drifting Snow ◽  
Snow Fence ◽  
Flow Turbulence ◽  
Deposition Models

Earlier works on numerical modelling are analysed. Anderson and Haff (1991) proposed a model using the “splash” function which was defined for cohesionless sand. The Uematsu and others (1989, 1991) and Liston and others (1993,1994) approaches are based on fluid-mechanics conservation laws where the snow is transported and diffused by the air flow. These models consider the saltation layer as a boundary condition.For the flow, and for the suspension, we adopt the same model as that of Uematsu and Liston. For mass exchange between the flow and snow surface, we have developed an erosion–deposition model where mass exchange is defined in relation to flow turbulence, threshold-friction velocity and snow concentration. Our snow-erosion model was calibrated using Takeuchi's(1980) field measurements. The deposition model was tested by comparing numerical results with wind-tunnel ones, for sawdust-accumulation windward and leeward of a solid snow fence with a bottom gap. The numerical results obtained are close to the experimental results. The main results of the various sensitivity experiments are: the leeward accumulation is very sensitive to the ratio (u*/u*t) (it appears for (u*/u*t) close to 1 and disappears for (u*/u*t) > 1.2), the global accumulation produced by the fence increases as (u*/u*t) decreases and the back reaction of particles on turbulence extends slightly the windward accumulation.

scholarly journals Numerical simulation of drifting snow: erosion and deposition models

1998 ◽  
Vol 26 ◽  
pp. 191-196 ◽  
Author(s):  
Mohamed Naaim ◽  
Florence Naaim-Bouvet ◽  
Hugo Martinez
Keyword(s):  
Mass Exchange ◽  
Field Measurements ◽  
Numerical Results ◽  
Back Reaction ◽  
Erosion And Deposition ◽  
Deposition Model ◽  
Drifting Snow ◽  
Snow Fence ◽  
Flow Turbulence ◽  
Deposition Models

Earlier works on numerical modelling are analysed. Anderson and Haff (1991) proposed a model using the “splash” function which was defined for cohesionless sand. The Uematsu and others (1989, 1991) and Liston and others (1993,1994) approaches are based on fluid-mechanics conservation laws where the snow is transported and diffused by the air flow. These models consider the saltation layer as a boundary condition.For the flow, and for the suspension, we adopt the same model as that of Uematsu and Liston. For mass exchange between the flow and snow surface, we have developed an erosion–deposition model where mass exchange is defined in relation to flow turbulence, threshold-friction velocity and snow concentration. Our snow-erosion model was calibrated using Takeuchi's(1980) field measurements. The deposition model was tested by comparing numerical results with wind-tunnel ones, for sawdust-accumulation windward and leeward of a solid snow fence with a bottom gap. The numerical results obtained are close to the experimental results. The main results of the various sensitivity experiments are: the leeward accumulation is very sensitive to the ratio (u*/u*t) (it appears for (u*/u*t) close to 1 and disappears for (u*/u*t) > 1.2), the global accumulation produced by the fence increases as (u*/u*t) decreases and the back reaction of particles on turbulence extends slightly the windward accumulation.

scholarly journals Numerical modeling of blowing and drifting snow in Alpine terrain

2001 ◽  
Vol 47 (156) ◽  
pp. 97-110 ◽  
Author(s):  
Peter Gauer
Keyword(s):  
Field Measurements ◽  
Erosion And Deposition ◽  
Mountainous Regions ◽  
Boundary Layer Equations ◽  
Trajectory Calculations ◽  
Drifting Snow ◽  
Physically Based ◽  
Turbulent Closure ◽  
Snow Distribution ◽  
Two Layer Model

AbstractIn mountainous regions, snow transport due to wind significantly influences snow distribution and, as a result, avalanche danger. A physically based numerical two-layer model is developed to simulate blowing and drifting snow in Alpine terrain. One layer describes the driving-wind field and the transport in suspension. The description is based on the atmospheric boundary-layer equations, using ane−∊model for the turbulent closure. The second layer describes the transport due to saltation, including erosion and deposition of snow. Here, conservation equations for mass and momentum are formulated for the mixture of snow and air. Particle trajectory calculations are used to parameterize quantities characterizing the saltation layer. Both layers are mutually coupled by boundary conditions. A two-way coupling between particles and airflow is taken into account. Comparisons between simulation results and field measurements around an Alpine crest show encouraging results.

scholarly journals Blowing and drifting snow in Alpine terrain: numerical simulation and related field measurements

1998 ◽  
Vol 26 ◽  
pp. 174-178 ◽  
Author(s):  
Peter Gauer
Keyword(s):  
Numerical Simulation ◽  
Numerical Model ◽  
Three Dimensional ◽  
Field Measurements ◽  
Blowing Snow ◽  
Related Field ◽  
Drifting Snow ◽  
Physically Based ◽  
Snow Transport

A physically based numerical model of drifting and blowing snow in three-dimensional terrain is developed. The model includes snow transport by saltation and suspension. As an example, a numerical simulation for an Alpine ridge is presented and compared with field measurements.

scholarly journals Field experiments on “living” snow fences

1998 ◽  
Vol 26 ◽  
pp. 217-220 ◽  
Author(s):  
Florence Naaim-Bouvet ◽  
Pierre Mullenbach
Keyword(s):  
Field Experiments ◽  
Snow Accumulation ◽  
Real Problem ◽  
Effective Height ◽  
Natural Plant ◽  
Drifting Snow ◽  
Snow Fence ◽  
Limited Scale ◽  
Living Fences ◽  
Snow Fences

In Franee, drifting snow is generally controlled using artificial snow fences. Living snow fences are not a new concept but they have only been used on a limited scale. Research directly related to natural plant barriers is limited. We therefore decided to study the behaviour of species that would survive and grow satisfactorily in the French Alps.In the first experiment, we compared the storage capacity of several different kinds of living fences consisting of pruned spruces, unpruned spruces and sorbs.Field observations during the winter of 1995-96 proved that deciduous trees such as sorbs are effective, and that pruning the lower 50 cm is not effective at the end of the season because of the weight of snow on low branches.However, the use of natural plant barriers has disadvantages: a living snow fence takes time to reach an effective height and is difficult to establish on windy sites at a high altitude. This is a real problem. Therefore, in a second experiment, we studied the death rate of larches planted behind a fence. We noticed that the snow fence had several effects, snow accumulation (until the planted trees grew up) and protection of the planted trees.

scholarly journals Nozzles, turbulence, and jet noise prediction

2018 ◽  
Vol 860 ◽  
pp. 1-4 ◽  
Author(s):  
Jonathan B. Freund
Keyword(s):  
Prediction Accuracy ◽  
Jet Noise ◽  
Sound Field ◽  
Field Measurements ◽  
Detailed Comparison ◽  
Large Eddy Simulations ◽  
Noise Prediction ◽  
Large Eddy ◽  
Modelling Procedure ◽  
Flow Turbulence

Jet noise prediction is notoriously challenging because only subtle features of the flow turbulence radiate sound. The article by Brès et al. (J. Fluid Mech., vol. 851, 2018, pp. 83–124) shows that a well-constructed modelling procedure for the nozzle turbulence can provide unprecedented sub-dB prediction accuracy with modest-scale large-eddy simulations, as confirmed by detailed comparison with turbulence and sound-field measurements. This both illuminates the essential mechanisms of the flow and facilitates prediction for engineering design.

scholarly journals Snow saltation threshold measurements in a drifting-snow wind tunnel

2006 ◽  
Vol 52 (179) ◽  
pp. 585-596 ◽  
Author(s):  
Andrew Clifton ◽  
Jean-Daniel Rüedi ◽  
Michael Lehning
Keyword(s):  
Particle Size ◽  
Wind Tunnel ◽  
Friction Velocity ◽  
Field Measurements ◽  
Drifting Snow ◽  
Velocity Relationship ◽  
Roughness Lengths ◽  
Surface Particle ◽  
Macroscopic Objects ◽  
Natural Snow

AbstractWind tunnel measurements of snowdrift in a turbulent, logarithmic velocity boundary layer have been made in Davos, Switzerland, using natural snow. Regression analysis gives the drift threshold friction velocity (u*t), assuming an exponential drift profile and a simple drift to friction velocity relationship. Measurements over 15 snow covers show that u*t is influenced more by snow density and particle size than by ambient temperature and humidity, and varies from 0.27 to 0.69 ms–1. Schmidt’s threshold algorithm and a modified version used in SNOWPACK (a snow-cover model) agree well with observations if small bond sizes are assumed. Using particle hydraulic diameters, obtained from image processing, Bagnold’s threshold parameter is 0.18. Roughness lengths (z0) vary between snow covers but are constant until the start of drift. Threshold roughness lengths are proportional to . The influence of macroscopic objects on the roughness length is shown by the lower values measured over the smooth and flat snow surface of the wind tunnel (0.04 ≤ z0 ≤ 0.13 mm), compared to field measurements. Mean drifting-snow grain sizes for mainly new and partly decomposed snow are 100–175 μm, and independent of surface particle size.

scholarly journals Six Years of Snow-Fence Testing in France

1989 ◽  
Vol 13 ◽  
pp. 16-19 ◽  
Author(s):  
G. Brugnot
Keyword(s):  
Test Site ◽  
Potential Hazard ◽  
Wind Action ◽  
Drifting Snow ◽  
Snow Fence ◽  
Geometrical Features ◽  
North Eastern ◽  
Pile Up

Drifting snow creates problems which have practical effects in France in two situations. The first situation is when the result of wind action on snow is to cause accumulation of this snow on mountains, leeward of crests, and consequently to create the potential hazard of avalanche. The second is when the result is to pile up snow in flat regions wherever there are obstacles such as road cuttings and vegetation. This paper focuses on the second type of problem, which affects large areas of central and north-eastern France. We explain how we have chosen our test site, which initial experiments we have conducted in order to assess the general geometrical features which a snow fence must possess in order to function most effectively in collecting snow, and how subsequently we have assessed the properties and costs of different fencing systems.

scholarly journals Drifting snow statistics from multiple-year autonomous measurements in Adelie Land, eastern Antarctica

2019 ◽  
Author(s):  
Charles Amory
Keyword(s):  
Temporal Frequency ◽  
Field Measurements ◽  
Near Surface ◽  
Continental Scale ◽  
Drifting Snow ◽  
Single Location ◽  
Antarctic Continent ◽  
Short Time ◽  
The Antarctic ◽  
Snow Transport

Abstract. Drifting snow is a widespread feature over the Antarctic ice sheet whose climatological and hydrological significances at the continental scale have been consequently investigated through modelling and satellite approaches. While field measurements are needed to evaluate and interpret model and punctual satellite products, most drifting snow observation campaigns in Antarctica involved data collected at a single location and over short time periods. With the aim of acquiring new data relevant to the observations and modelling of drifting snow in Antarctic conditions, two remote locations in coastal Adelie Land (East Antarctica) 100 km apart were instrumented in January 2010 with meteorological and second-generation IAV Engineering acoustic FlowCaptTM sensors. The data provided nearly continuously so far constitutes the longest dataset of autonomous near-surface (i.e., below 2 m) measurements of drifting snow currently available over the Antarctic continent. This paper presents an assessment of drifting snow occurrences and snow mass transport from up to 9 years (2010–2018) of half-hourly observational records collected in one of the Antarctic regions most prone to snow transport by wind. The dataset is freely available to the scientific community and can be used to complement satellite products and evaluate snow-transport models close to the surface and at high temporal frequency.

scholarly journals Six Years of Snow-Fence Testing in France

1989 ◽  
Vol 13 ◽  
pp. 16-19 ◽  
Author(s):  
G. Brugnot
Keyword(s):  
Test Site ◽  
Potential Hazard ◽  
Wind Action ◽  
Drifting Snow ◽  
Snow Fence ◽  
Geometrical Features ◽  
North Eastern ◽  
Pile Up

Drifting snow creates problems which have practical effects in France in two situations. The first situation is when the result of wind action on snow is to cause accumulation of this snow on mountains, leeward of crests, and consequently to create the potential hazard of avalanche. The second is when the result is to pile up snow in flat regions wherever there are obstacles such as road cuttings and vegetation. This paper focuses on the second type of problem, which affects large areas of central and north-eastern France. We explain how we have chosen our test site, which initial experiments we have conducted in order to assess the general geometrical features which a snow fence must possess in order to function most effectively in collecting snow, and how subsequently we have assessed the properties and costs of different fencing systems.

scholarly journals Design Criteria and Location of Snow Fences

1985 ◽  
Vol 6 ◽  
pp. 68-70
Author(s):  
Harald Norem
Keyword(s):  
Minimum Distance ◽  
Storage Capacity ◽  
Windward Side ◽  
Design Criteria ◽  
Total Density ◽  
Design Considerations ◽  
Drifting Snow ◽  
Snow Fence ◽  
Snow Model ◽  
Snow Fences

The paper describes experience gained in Norway regarding the design criteria and use in practice of snow fences. The paper is based on theoretical studies on drifting snow, model experiments and experience accumulated through practical consulting work.Snow fence design is a compromise between the storage capacity and minimization of dimensioning forces. Design considerations include fence height H, total snow fence density, and the gap between ground and fence. A gap of 0.15H - 0.2H and a total density of 45% are usually recommended. On ridge crests the gap can be reduced to 0.1H and in areas where snow depths exceed 2.0 m, it can be increased to 0.3H. In such cases the fence density should be varied such that the total density, including the gap, will remain near 45%. The height of the snow fences should be kept within 3.5 -4.5 m and the snow fences should be erected on the windward side of obstacles that create snowdrifts. The minimum distance from fence to road should not be less than 15H; in certain circumstances in coastal climate, this can be reduced to 10H.

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