scholarly journals Three-dimensional simulation of non-uniform sediment transport based on multi-phase Eulerian approach: Application to debris flow

2018 ◽  
Vol 40 ◽  
pp. 05051
Author(s):  
Kazuyuki Ota ◽  
Hitoshi Suto ◽  
Takahiro Sato
Keyword(s):  
Numerical Model ◽  
Debris Flow ◽  
Large Scale ◽  
Three Dimensional ◽  
Flow Property ◽  
Size Segregation ◽  
Particle Collisions ◽  
Sediment Size ◽  
Dimensional Simulation ◽  
Multi Phase

To simulate 3D flow of a non-uniform and highly concentrated sediment, a numerical model using a multi-phase Eulerian method for air, water, and particles of various class size is developed. This model accounts for turbulence in pore water, particle-particle collisions, and enduring friction. To test its performance, simulations were performed for large scale debris-flow experiments. The numerical model reproduces successfully the flow property and sediment size segregation of the debris flow.

Three-dimensional simulation of large-scale structure in the Universe

Nature ◽  
1983 ◽  
Vol 305 (5931) ◽  
pp. 196-198 ◽  
Author(s):  
Joan Centrella ◽  
Adrian L. Melott
Keyword(s):  
Large Scale ◽  
Three Dimensional ◽  
Large Scale Structure ◽  
Scale Structure ◽  
Dimensional Simulation ◽  
The Universe

scholarly journals A THREE-DIMENSIONAL SIMULATION AND VISUALIZATION SYSTEM FOR UAV PHOTOGRAMMETRY

2017 ◽  
Vol XLII-2/W6 ◽  
pp. 217-222 ◽  
Author(s):  
Y. Liang ◽  
Y. Qu ◽  
T. Cui
Keyword(s):  
Large Scale ◽  
Three Dimensional ◽  
Cost Effective ◽  
Three Dimensions ◽  
Wind Condition ◽  
Plan Evaluation ◽  
Visualization System ◽  
Flight Plan ◽  
Aerial Photogrammetry ◽  
Dimensional Simulation

Nowadays UAVs has been widely used for large-scale surveying and mapping. Compared with manned aircraft, UAVs are more cost-effective and responsive. However, UAVs are usually more sensitive to wind condition, which greatly influences their positions and orientations. The flight height of a UAV is relative low, and the relief of the terrain may result in serious occlusions. Moreover, the observations acquired by the Position and Orientation System (POS) are usually less accurate than those acquired in manned aerial photogrammetry. All of these factors bring in uncertainties to UAV photogrammetry. To investigate these uncertainties, a three-dimensional simulation and visualization system has been developed. The system is demonstrated with flight plan evaluation, image matching, POS-supported direct georeferencing, and ortho-mosaicing. Experimental results show that the presented system is effective for flight plan evaluation. The generated image pairs are accurate and false matches can be effectively filtered. The presented system dynamically visualizes the results of direct georeferencing in three-dimensions, which is informative and effective for real-time target tracking and positioning. The dynamically generated orthomosaic can be used in emergency applications. The presented system has also been used for teaching theories and applications of UAV photogrammetry.

scholarly journals Debris-Flow Hazard Assessments: A Practitioner's View

2021 ◽  
Author(s):  
Matthias Jakob
Keyword(s):  
Debris Flow ◽  
Debris Flows ◽  
Three Dimensional ◽  
Extreme Value Statistics ◽  
Major Life ◽  
Two Factors ◽  
Hazard Assessments ◽  
Cost Efficient ◽  
Multi Phase ◽  
Debris Flow Hazard

ABSTRACT Substantial advances have been achieved in various aspects of debris-flow hazard assessments over the past decade. These advances include sophisticated ways to date previous events, two- and three-dimensional runout models including multi-phase flows and debris entrainment options, and applications of extreme value statistics to assemble frequency–magnitude analyses. Pertinent questions have remained the same: How often, how big, how fast, how deep, how intense, and how far? Similarly, although major life loss attributable to debris flows can often, but not always, be avoided in developed nations, debris flows remain one of the principal geophysical killers in mountainous terrains. Substantial differences in debris-flow hazard persist between nations. Some rely on a design magnitude associated with a specific return period; others use relationships between intensity and frequency; and some allow for, but do not mandate, in-depth quantitative risk assessments. Differences exist in the management of debris-flow risks, from highly sophisticated and nation-wide applied protocols to retroaction in which catastrophic debris flows occur before they are considered for mitigation. Two factors conspire to challenge future generations of debris-flow researchers, practitioners, and decision makers: Population growth and climate change, which are increasingly manifested by augmenting hydroclimatic extremes. While researchers will undoubtedly finesse future remote sensing, dating, and runout techniques and models, practitioners will need to focus on translating those advances into practical cost-efficient tools and integrating those tools into long-term debris-flow risk management.

scholarly journals DebrisInterMixing-2.3: a finite volume solver for three-dimensional debris-flow simulations with two calibration parameters – Part 2: Model validation

2017 ◽  
Author(s):  
Albrecht v. Boetticher ◽  
Jens M. Turowski ◽  
Brian W. McArdell ◽  
Dieter Rickenmann ◽  
Marcel Hürlimann ◽  
...  
Keyword(s):  
Debris Flow ◽  
Model Validation ◽  
Material Properties ◽  
Large Scale ◽  
Fluid Dynamic ◽  
Three Dimensional ◽  
Clay Content ◽  
Friction Angle ◽  
Angle Of Repose ◽  
Model Parameters

Abstract. Here we present validation tests of the fluid dynamic solver presented in in v. Boetticher et al. (2016), simulating both laboratory-scale and large-scale debris-flow experiments. The new solver combines a Coulomb viscosplastic rheological model with a Herschel-Bulkley model based on material properties and rheological characteristics of the analysed debris flow. For the selected experiments in this study, all necessary material properties were known – the content of sand, clay (including its mineral composition) and gravel (including its friction angle) as well as the water content. We show that given these measured properties, two model parameters are sufficient for calibration, and a range of experiments with different material compositions can be reproduced by the model without recalibration. One calibration parameter, the Herschel–Bulkley exponent, was kept constant for all simulations. The model validation focuses on different case studies illustrating the sensitivity of debris flows to water and clay content, channel curvature, channel roughness and the angle of repose. We characterize the accuracy of the model using experimental observations of flow head positions, front velocities, run-out patterns and basal pressures.

Simulating air distribution system for civil aircraft

2021 ◽  
Author(s):  
S.N. Gusarkin ◽  
Skidanov S.N.
Keyword(s):  
Numerical Model ◽  
Distribution System ◽  
Block Diagram ◽  
Empirical Test ◽  
Three Dimensional ◽  
System Structure ◽  
Air Distribution ◽  
Civil Aircraft ◽  
Dimensional Simulation ◽  
System Prototype

The paper considers an air distribution system for a pressurized cabin in a civil aircraft. We propose a method for simulating this system that involves developing a one-dimensional model based on hydraulic computation results for the three-dimensional geometry of the distribution system structure. This approach makes it possible to recompute air distribution in large branching systems relatively quickly and with sufficient accuracy when making changes to their design. The advantages of this method include lower computing costs and lower labour intensity compared to using a modern CFD software package to simulate a full three-dimensional flow in the distribution system structure. The paper describes the operation of the air distribution system prototype and presents the schematic diagram and the functional flow block diagram of the system. We show how to use three-dimensional simulation to determine the discharge characteristics of system pipelines. We present the numerical model constructed for the system and display the capabilities of this model in static and dynamic simulation modes. We analysed the simulation results and confirmed the possibility of using the method proposed for engineering computations. We validated the numerical model using experimental investigation results obtained by means of an empirical test bench simulating the air distribution system prototype.

MPF-FDTD Simulations of Fabrication and Optical Analysis of Ordered Gold Nano-Dots Array

2012 ◽  
Vol 523-524 ◽  
pp. 621-626
Author(s):  
Akinori Yamanaka ◽  
Zhen Xing Li ◽  
Masahiko Yoshino
Keyword(s):  
Three Dimensional ◽  
Field Method ◽  
Phase Field Method ◽  
Localized Surface Plasmon ◽  
Optical Analysis ◽  
Optical Responses ◽  
Plastic Forming ◽  
Dimensional Simulation ◽  
Multi Phase ◽  
Difference Time

Recently, the authors have proposed a hybrid fabrication method of an ordered gold nano-dots array using a combination of the nano plastic forming and thermal annealing. In this study, in order to investigate morphology and optical properties of the gold nano-dots array fabricated by the proposed method, we develop a coupled three-dimensional simulation model by using the multi-phase-field method and the finite-difference-time-domain method. The simulation results demonstrate that the ordered gold nano-dots array which can be obtained by the proposed method exhibits quite characteristic optical responses due to the localized surface plasmon resonance.

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