scholarly journals Snow avalanche friction relation based on extended kinetic theory

2016 ◽  
Author(s):  
Matthias Rauter ◽  
Jan-Thomas Fischer ◽  
Wolfgang Fellin ◽  
Andreas Kofler
Keyword(s):  
Kinetic Theory ◽  
Three Dimensional ◽  
Field Tests ◽  
Friction Model ◽  
Snow Avalanche ◽  
Snow Avalanches ◽  
Rheological Models ◽  
Physically Based Model ◽  
Physically Based

Abstract. Rheological models for granular materials play an important role in the numerical simulation of dry dense snow avalanches. This article describes the application of a physically based model from the field of kinetic theory to snow avalanche simulations. Those are usually based on depth-averaged two-dimensional models. Therefore a method to adapt the three-dimensional rheological model is presented. In a further step simulation results are compared to velocity and runout observations of avalanches, recorded from different field tests. As reference we utilize a classic phenomenological friction model, which is commonly applied for hazard estimation. The quantitative comparison is based on the combination of normalized residuals of different observation variables in order to take into account the quality of the simulations in various regards. It is demonstrated that the kinetic theory provides a physically based explanation for the structure of phenomenological friction relations and contributes improvements, in particular when different events and various observation variables are investigated.

scholarly journals Snow avalanche friction relation based on extended kinetic theory

2016 ◽  
Vol 16 (11) ◽  
pp. 2325-2345 ◽  
Author(s):  
Matthias Rauter ◽  
Jan-Thomas Fischer ◽  
Wolfgang Fellin ◽  
Andreas Kofler
Keyword(s):  
Kinetic Theory ◽  
Field Tests ◽  
Simulation Software ◽  
Snow Avalanche ◽  
Snow Avalanches ◽  
Rheological Models ◽  
Physically Based Model ◽  
Physically Based ◽  
Basic Features

Abstract. Rheological models for granular materials play an important role in the numerical simulation of dry dense snow avalanches. This article describes the application of a physically based model from the field of kinetic theory to snow avalanche simulations. The fundamental structure of the so-called extended kinetic theory is outlined and the decisive model behavior for avalanches is identified. A simplified relation, covering the basic features of the extended kinetic theory, is developed and implemented into an operational avalanche simulation software. To test the obtained friction relation, simulation results are compared to velocity and runout observations of avalanches, recorded from different field tests. As reference we utilize a classic phenomenological friction relation, which is commonly applied for hazard estimation. The quantitative comparison is based on the combination of normalized residuals of different observation variables in order to take into account the quality of the simulations in various regards. It is demonstrated that the extended kinetic theory provides a physically based explanation for the structure of phenomenological friction relations. The friction relation derived with the help of the extended kinetic theory shows advantages to the classic phenomenological friction, in particular when different events and various observation variables are investigated.

The Daisy agroecological system model: A physically based model for preferential water flow and solute transport in drained agricultural fields

2021 ◽  
Author(s):  
Efstathios Diamantopoulos ◽  
Maja Holbak ◽  
Per Abrahamsen
Keyword(s):  
Solute Transport ◽  
Water Flow ◽  
Preferential Flow ◽  
Column Experiment ◽  
Soil Matrix ◽  
Physically Based Model ◽  
Physically Based ◽  
Rapid Transport ◽  
Preferential Water

<p>Preferential water flow and solute transport in agricultural systems affects not only the quality of groundwater but also the quality of surface waters like streams and lakes. This is due to the rapid transport of agrochemicals, immediately after application, through subsurface drainpipes and surface water. Experimental evidence attributes this to the occurrence of continuously connected pathways, connecting the soil surface directly with the drainpipes. We developed a physically-based model describing preferential flow and transport in biopores and implemented it in the agroecological model Daisy. The model simulates the often observed rapid transport of chemicals from   the upper soil layers to the drainpipes or to deeper layers of the soil matrix. Based on field investigations, biopores with specific characteristics can be parameterized as classes with different vertical and horizontal distributions. The model was tested against experimental data from a column experiment with an artificial biopore and showed good results in simulating preferential flow dynamics. We illustrate the performance of the new approach, by conducting five simulations assuming a two-dimensional simulation domain with different biopore parametrizations, from none to several different classes. The simulation results agreed with experimental observations reported in the literature, indicating rapid transport from the soil to the drainpipes. Furthermore, the different biopore parametrizations resulted in distinctly different leaching patterns, raising the expectation that biopore properties could be estimated or constrained based on observed leaching data and direct measurements.</p>

Modeling of snow avalanche dynamics using open source software OpenFOAM

2021 ◽  
Author(s):  
Daria Romanova ◽  
Margarita Egiit
Keyword(s):  
Three Dimensional ◽  
Snow Avalanche ◽  
Machine Learning Techniques ◽  
Turbulent Regime ◽  
Snow Avalanches ◽  
Advantages And Disadvantages ◽  
Three Dimensional Modeling ◽  
The Neural Network ◽  
Learning Techniques ◽  
Protective Structures

<p>The work is devoted to the comparison of different approaches for modeling the dynamics of dense and powder snow avalanches. Various 3D and 2D approaches are considered. The accuracy of determining the avalanche run-out zone, the interaction of the flow with obstacles, the front speed, and various distributed parameters are evaluated. As objects for comparison, an experiment on the interaction of a slushflow with a combination of protective structures and a powder snow avalanche in the Khibiny mountains are modeled.</p><p> </p><p>Taking into account the advantages and disadvantages of various approaches based on basic solutions available in the OpenFOAM package, a specialized software avalancheFoam is being developed for three-dimensional modeling of the dynamics of snow avalanches, taking into account the complex turbulent regime and multiphase structure of the flow. Machine learning techniques are used to refine turbulent stresses. The neural network is trained on a dataset obtained from high-precision supercomputer simulation of the flow, and sets the form of additional refinement members of the mathematical model of less computational complexity. Various avalanche sites in the Khibiny mountains are modeled to validate the developed software.</p>

scholarly journals Three-dimensional and real-scale modeling of flow regimes in dense snow avalanches

Landslides ◽  
2021 ◽  
Author(s):  
Xingyue Li ◽  
Betty Sovilla ◽  
Chenfanfu Jiang ◽  
Johan Gaume
Keyword(s):  
Three Dimensional ◽  
Economic Loss ◽  
Density Variation ◽  
Material Point ◽  
Snow Avalanche ◽  
Snow Avalanches ◽  
Computationally Efficient ◽  
Mountainous Regions ◽  
Depth Direction ◽  
Wide Range

AbstractSnow avalanches cause fatalities and economic loss worldwide and are one of the most dangerous gravitational hazards in mountainous regions. Various flow behaviors have been reported in snow avalanches, making them challenging to be thoroughly understood and mitigated. Existing popular numerical approaches for modeling snow avalanches predominantly adopt depth-averaged models, which are computationally efficient but fail to capture important features along the flow depth direction such as densification and granulation. This study applies a three-dimensional (3D) material point method (MPM) to explore snow avalanches in different regimes on a complex real terrain. Flow features of the snow avalanches from release to deposition are comprehensively characterized for identification of the different regimes. In particular, brittle and ductile fractures are identified in the different modeled avalanches shortly after their release. During the flow, the analysis of local snow density variation reveals that snow granulation requires an appropriate combination of snow fracture and compaction. In contrast, cohesionless granular flows and plug flows are mainly governed by expansion and compaction hardening, respectively. Distinct textures of avalanche deposits are characterized, including a smooth surface, rough surfaces with snow granules, as well as a surface showing compacting shear planes often reported in wet snow avalanche deposits. Finally, the MPM modeling is verified with a real snow avalanche that occurred at Vallée de la Sionne, Switzerland. The MPM framework has been proven as a promising numerical tool for exploring complex behavior of a wide range of snow avalanches in different regimes to better understand avalanche dynamics. In the future, this framework can be extended to study other types of gravitational mass movements such as rock/glacier avalanches and debris flows with implementation of modified constitutive laws.

Study the precision of creating 3D structure modeling form terrestrial laser scanner observations

2018 ◽  
Vol 12 (4) ◽  
pp. 303-309
Author(s):  
Zaki M. Zeidan ◽  
Ashraf A. Beshr ◽  
Ashraf G. Shehata
Keyword(s):  
Structural Model ◽  
3D Structure ◽  
Three Dimensional ◽  
Laser Scanner ◽  
Field Tests ◽  
3D Models ◽  
Terrestrial Laser Scanner ◽  
Analysis Of Results ◽  
3D Structure Modeling

Abstract Laser scanner has become widely used nowadays for several applications in civil engineering. An advantage of laser scanner as compared to other geodetic instruments is its capability of collecting hundreds or even thousands of point per second. Terrestrial laser scanner allows acquiring easy and fast complex geometric data from building, machines, objects, etc. Several experimental and field tests are required to investigate the quality and accuracy of scanner points cloud and the 3D geometric models derived from laser scanner. So this paper investigates the precision of creation three dimensional structural model resulted from terrestrial laser scanner observations. The paper also presented the ability to create 3D model by structural faces depending on the plane equation for each face resulted from coordinates of several observed points cover this face using reflector less total station observations. Precision comparison for the quality of 3D models created from laser scanner observations and structure faces is also presented.The results of the practical measurements, calculations and analysis of results are presented.

Modeling of Underwater Flexible Structures and Its Application to the Fishing Gear System Simulation

2004 ◽  
Author(s):  
Chun-Woo Lee ◽  
Ju-Hee Lee ◽  
Bong-Jin Cha ◽  
Hyun-Young Kim ◽  
Ji-Hoon Lee
Keyword(s):  
Flexible Structures ◽  
Three Dimensional ◽  
Stable Solution ◽  
Commercial Fishing ◽  
Flexible Systems ◽  
Physically Based Model ◽  
Mass Spring Model ◽  
Physically Based ◽  
External Forces ◽  
Mass Spring

This paper describes a physically based model for underwater flexible systems and presents its simulation results. In this study, a flexible structure is divided into a finite number of elements and those elements are connected with flexible lines. The elements of a structure can be modeled using the mass-spring model. The model is described as a nonlinear and stiff equation by considering the elasticity of the lines and external forces. The Newmark β method is used for the numerical integration of the system. It is found that this method offers low computational times and a stable solution. Also introduced is an algorithm to design various flexible systems using computer graphics, an automatic model creating system from the designed plan and a three-dimensional graphics tool that can show the calculated results. Application examples in design and simulation for the commercial fishing gears are presented.

Scanning Electron Microscopy in Hybrid Microelectronics

1976 ◽  
Vol 34 ◽  
pp. 456-457
Author(s):  
S. Khadpe ◽  
R. Faryniak
Keyword(s):  
Integrated Circuits ◽  
Thick Film ◽  
Integrated Circuit ◽  
Failure Modes ◽  
Three Dimensional ◽  
Circuit Components ◽  
Hybrid Microcircuit ◽  
Electrical Connections ◽  
Scanning Electron

The Scanning Electron Microscope (SEM) is an important tool in Thick Film Hybrid Microcircuits Manufacturing because of its large depth of focus and three dimensional capability. This paper discusses some of the important areas in which the SEM is used to monitor process control and component failure modes during the various stages of manufacture of a typical hybrid microcircuit.Figure 1 shows a thick film hybrid microcircuit used in a Motorola Paging Receiver. The circuit consists of thick film resistors and conductors screened and fired on a ceramic (aluminum oxide) substrate. Two integrated circuit dice are bonded to the conductors by means of conductive epoxy and electrical connections from each integrated circuit to the substrate are made by ultrasonically bonding 1 mil aluminum wires from the die pads to appropriate conductor pads on the substrate. In addition to the integrated circuits and the resistors, the circuit includes seven chip capacitors soldered onto the substrate. Some of the important considerations involved in the selection and reliability aspects of the hybrid circuit components are: (a) the quality of the substrate; (b) the surface structure of the thick film conductors; (c) the metallization characteristics of the integrated circuit; and (d) the quality of the wire bond interconnections.

Semi-automated methods for 3-D reconstruction of macromolecular complexes

1995 ◽  
Vol 53 ◽  
pp. 42-43
Author(s):  
B. Carragher ◽  
M. Whittaker
Keyword(s):  
Three Dimensional ◽  
Time Saving ◽  
Macromolecular Complexes ◽  
Symmetry Properties ◽  
Dimensional Reconstruction ◽  
Experienced Operator ◽  
Projection Images ◽  
The Individual ◽  
Natural Symmetry

Techniques for three-dimensional reconstruction of macromolecular complexes from electron micrographs have been successfully used for many years. These include methods which take advantage of the natural symmetry properties of the structure (for example helical or icosahedral) as well as those that use single axis or other tilting geometries to reconstruct from a set of projection images. These techniques have traditionally relied on a very experienced operator to manually perform the often numerous and time consuming steps required to obtain the final reconstruction. While the guidance and oversight of an experienced and critical operator will always be an essential component of these techniques, recent advances in computer technology, microprocessor controlled microscopes and the availability of high quality CCD cameras have provided the means to automate many of the individual steps.During the acquisition of data automation provides benefits not only in terms of convenience and time saving but also in circumstances where manual procedures limit the quality of the final reconstruction.

Towards Predicting Relative Belt Edge Endurance With the Finite Element Method

1990 ◽  
Vol 18 (4) ◽  
pp. 216-235 ◽  
Author(s):  
J. De Eskinazi ◽  
K. Ishihara ◽  
H. Volk ◽  
T. C. Warholic
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Three Dimensional ◽  
The Finite Element Method ◽  
Shear Deformations ◽  
Element Analysis ◽  
Vertical Loading ◽  
Predicted Values ◽  
Element Method

Abstract The paper describes the intention of the authors to determine whether it is possible to predict relative belt edge endurance for radial passenger car tires using the finite element method. Three groups of tires with different belt edge configurations were tested on a fleet test in an attempt to validate predictions from the finite element results. A two-dimensional, axisymmetric finite element analysis was first used to determine if the results from such an analysis, with emphasis on the shear deformations between the belts, could be used to predict a relative ranking for belt edge endurance. It is shown that such an analysis can lead to erroneous conclusions. A three-dimensional analysis in which tires are modeled under free rotation and static vertical loading was performed next. This approach resulted in an improvement in the quality of the correlations. The differences in the predicted values of various stress analysis parameters for the three belt edge configurations are studied and their implication on predicting belt edge endurance is discussed.

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