A Study on Model Experiments and Numerical Simulations on Rockfalls and Its Utilization to Assess the Rockfall Hazards in Miyagi Island (Japan) and Cappadocia (Turkey)

2021 ◽  
pp. 482-490
Author(s):  
Nazlı Tunar Özcan ◽  
Ömer Aydan ◽  
Yuuki Murayama ◽  
Kouki Horiuchi ◽  
Reşat Ulusay
Keyword(s):  
Numerical Simulations ◽  
Model Experiments ◽  
Rockfall Hazards

Eddy Current Flow Meter Performance in Liquid Metal Flows Inclined to the Sensor Axis

2021 ◽  
Author(s):  
Nico Krauter ◽  
Vladimir Galindo ◽  
Thomas Wondrak ◽  
Sven Eckert ◽  
Gunter Gerbeth
Keyword(s):  
Liquid Metal ◽  
Numerical Simulations ◽  
Eddy Current ◽  
Current Flow ◽  
Fast Reactors ◽  
Flow Meter ◽  
Flow Angle ◽  
Model Experiments ◽  
Inductive Sensor ◽  
Pipe Flows

Abstract The Eddy Current Flow Meter is a reliable and robust inductive sensor for the measurement of flowrates in liquid metal flows. This kind of sensor is usually being used in pipe flows where the flow is mostly parallel to the sensor axis. When this sensor is used as part of the safety instrumentation above the subassemblies in liquid metal cooled fast reactors, the flow angle may change rapidly according to the conditions within the reactor. In this paper we investigate the performance of the Eddy Current Flow Meter in flows inclined to the sensor axis by numerical simulations as well as model experiments. We demonstrate that the Eddy Current Flow Meter yields reliable results for flow angles up to 30° while the sensitivity of the sensor is significantly reduced for larger angles.

Numerical Simulation and Experimental Validation on the Surf-Riding and Broaching of a Fishing Vessel

2016 ◽  
Author(s):  
Liwei Yu ◽  
Ning Ma ◽  
Sheming Fan ◽  
Peiyuan Feng ◽  
Xiechong Gu
Keyword(s):  
Numerical Simulation ◽  
Numerical Simulations ◽  
Model Test ◽  
Periodic Motion ◽  
Following Seas ◽  
Weakly Nonlinear ◽  
Model Experiments ◽  
Time Histories ◽  
Wave Heights ◽  
Surf Riding

Model experiments and numerical simulations on the surf-riding and broaching in following seas of a 42.5m long purse seiner are conducted. Firstly, the free running model experiments with various ship speeds and wave heights are performed in the towing tank to reproduce the phenomena of surf-riding and broaching. Then, the 6-DOF weakly nonlinear unified model is applied to simulate the motions of the purse seiner with the same cases as the model experiments. Through the comparison between results of model test and numerical simulation, the occurrence conditions of periodic motion, surf-riding and broaching are roughly determined. Finally, it is found that although it is difficult for the numerical simulations to get the same time histories as model tests, the modes of motion (periodic motion, surf-riding or broaching) obtained from the numerical simulations agree well qualitatively and quantitatively in part with the model test results.

An Investigation on the Excitation of Yaw Parametric Resonance of a Tension Leg Platform

2012 ◽  
Author(s):  
Roberto Edward Cruz ◽  
Marcelo A. S. Neves ◽  
Luis Alberto Rivera ◽  
Paulo T. T. Esperança
Keyword(s):  
Mathematical Model ◽  
Time Series ◽  
Numerical Simulations ◽  
Parametric Resonance ◽  
Hydrodynamic Interactions ◽  
Tension Leg Platform ◽  
Model Experiments ◽  
Close Proximity ◽  
Sway Motion ◽  
Adequate Agreement

The paper summarizes some aspects of a series of model experiments conducted with a Tension Leg Platform (in fact a Tension Leg Wellhead Platform) in close proximity with a FPSO emphasizing the types of coupled motions taking place. It is observed that as the yaw motion develops increasing amplitudes the sway motion is reduced, pointing out to an interesting exchange of energy between the sway and yaw modes. This should be recognized as a revealing aspect of strongly non-linear coupled parametric resonant motions. A mathematical model is proposed to describe the main aspects of the two-body moored system and hydrodynamic interactions. In principle a 12-DOF model is contemplated. Numerical simulations are compared to the time series obtained from the experiments showing adequate agreement. However, in this paper the essential coupling of sway and yaw is distinguished in order to typify the Mathieu-type instability as being the main mechanism behind the onset of large yaw motions of the TLP unit.

scholarly journals Parameter Optimization of Geogrid-Reinforced Foundations Based on Model Experiments and Numerical Simulations

2019 ◽  
Vol 9 (17) ◽  
pp. 3592
Author(s):  
Guolong Zhang ◽  
Yuyou Yang ◽  
Fei Su
Keyword(s):  
Numerical Simulations ◽  
Linear Regression Analysis ◽  
Earth Pressure ◽  
Reinforced Soil ◽  
Dynamic Compaction ◽  
Design Parameters ◽  
Range Analysis ◽  
Model Experiments ◽  
Five Factors ◽  
Field Compaction

Dynamic compaction and geogrid reinforcement are two of the well-known methods used in improving the mechanical properties of fill foundations. In order to investigate their mutual restriction when used simultaneously and optimize the design parameters, model experiments and numerical simulations were conducted. First, three factors (embedded ratio of reinforced geogrid, number of reinforced layers and interval of reinforced layers) that are related to performance of reinforced geogrid were analyzed by model experiments with dynamic compaction. Then, orthogonal analysis was performed by numerical simulation (dynamic analysis in FLAC3D) to take into account five different elastic moduli and internal angle of friction along with the aforementioned three factors. Last, range analysis and variance analysis were performed on the orthogonal results to optimize the five factors by the calculated indicators. Additionally, linear regression analysis reflecting the relationships between five factors and four indicators was presented. The displacement field, compaction effect, earth pressure, and geogrid deformation of the reinforced soil under different combinations of the five factors were explored. Experiment and simulation results provide practical guides to the design of reinforced methods and a reference for the stability and deformation of other earth reinforcement projects under dynamic loads.

scholarly journals Engineering Application and Prediction of the Influence Area of the Rockfall Hazards

2020 ◽  
Vol 2020 ◽  
pp. 1-14
Author(s):  
Xiaohui Liao ◽  
Xueliang Wang ◽  
Lihui Li ◽  
Haiyang Liu ◽  
Zhifa Yang ◽  
...  
Keyword(s):  
Tensile Stress ◽  
Numerical Simulations ◽  
Rock Slope ◽  
Horizontal Distance ◽  
Weathered Rock ◽  
Plastic Failure ◽  
Influence Area ◽  
Field Investigations ◽  
Rockfall Hazards

The identification of potential rockfall and the accurate prediction of its trajectory are critical in prevention and mitigation of rockfall hazard. It is an important precondition to assess the uncertainty of rockfall motion, study the effective identification technology of potential rockfall, predict the rockfall trajectory, and calculate the threatened area by rockfall hazards. In this study, field investigations and numerical simulations were carried out to identify potential rockfall on a weathered rock slope. As a case study, our calculations results show that the area of tensile stress concentration and plastic failure is the potential area where the rockmass will fall off the surface of the weathered rock slope. A mathematical model for calculating the rockfall influence area of the weathered rock slope was established based on the optimization theory, neural network technology, and genetic optimization algorithm. The rockfall influence area of the weathered rock slope was determined using maximum horizontal distance of rockfall in the specified slope cross sections and described on the topographic map using spline curves to form a closed possibly vulnerable area. As a case study, our calculations confirm that the distributions of the plastic failure and tensile stress areas obtained from the numerical simulations are consistent with the dangerous rock masses identified by field investigations at Guanyindong Slope that is a popular tourist scenic spot in Zhejiang Province, China. In this study, it has been indicated that the influence area can be used as the basis for the design of passive protection methods for rock slopes vulnerable to rockfall hazards.

scholarly journals Model experiments and numerical simulations of sloshing and swirling in membrane LNG tanks

2018 ◽  
Vol 27 (0) ◽  
pp. 107-115
Author(s):  
Tomomi Yoshida ◽  
Makoto Arai ◽  
Gustavo Massaki Karuka ◽  
Yuka Akiyama ◽  
Hideyuki Ando
Keyword(s):  
Numerical Simulations ◽  
Model Experiments

Dynamic Response and Stability of Un-Reinforced and Reinforced Rock Slopes Against Planar Sliding Subjected to Ground Shaking

2018 ◽  
Vol 12 (04) ◽  
pp. 1841001 ◽  
Author(s):  
Ö. Aydan ◽  
Y. Takahashi ◽  
N. Iwata ◽  
R. Kiyota ◽  
K. Adachi
Keyword(s):  
Dynamic Response ◽  
Numerical Simulations ◽  
Model Tests ◽  
Rock Slopes ◽  
Scaled Model ◽  
Ground Shaking ◽  
Model Experiments ◽  
Actual Rock

The authors have been performing some scaled model tests to investigate the response and stability of rock slopes against planar sliding. In these tests, rockbolts/rockanchors are modeled and their reinforcement effects on rock slopes against planar sliding during ground shaking are investigated. These model tests are also used to check the reliability of the numerical simulations. The authors present the outcomes of both model experiments and numerical simulations and compare their implications on actual rock slopes.

Sound Fields in and around Railway Line Cuttings

2009 ◽  
Vol 40 (9) ◽  
pp. 12-19
Author(s):  
Kurt Heutschi
Keyword(s):  
Numerical Simulations ◽  
Calculation Scheme ◽  
Scale Model ◽  
Model Experiments ◽  
Sound Fields ◽  
Railway Line ◽  
Railway Noise ◽  
Semi Empirical ◽  
Noise Models

Sound fields in and around railway line cuttings are often strongly influenced by reflections between the cutting walls and between cutting walls and train body. The relevance of these reflections was investigated by scale model experiments and by numerical simulations. Based on these findings a semi-empirical calculation scheme was developed that allows for an estimation of sound fields in the surroundings of railway line cuttings. The calculation scheme is designed for easy incorporation into existing engineering railway noise models.

scholarly journals EVALUATION OF VEGETATED DUNES FOR EROSION RESISTANCE AGAINST TSUNAMI OVERFLOW

2020 ◽  
pp. 30
Author(s):  
Kunihiro Watanabe ◽  
Fuminori Kato
Keyword(s):  
Numerical Simulations ◽  
Erosion Resistance ◽  
Sand Dunes ◽  
Hydraulic Model ◽  
Soil Samples ◽  
Root Density ◽  
Erosion Model ◽  
Model Experiments ◽  
Japanese Coast ◽  
The Relationship

A total of 14 soil samples were collected from sand dunes without scattering, and the process of tsunami-induced erosion was observed using hydraulic model experiments. The densities of vegetation roots were measured at 45 points on seven beaches along the Japanese coast. The results of the experiment confirmed that the roots of vegetation highly affected the resistance of soil against erosion. Based on this result, an erosion model based on the index alpha was proposed, and the relationship between alpha and root density was described. Then, the applicability of the proposed erosion model was investigated using numerical simulations.

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