Coupled motion characteristics of a large-scale tunnel element suspended by immersion rigs in the vicinity of seabed

Tank sloshing is widely present in many engineering fields, especially in the field of marine. Due to the trend of large-scale liquid cargo ships, it is of great significance to study the coupled motion response of ships with tanks in beam waves. In this study, the CFD (Computational Fluid Dynamics) method and experiments are used to study the response of a ship with/without a tank in beam waves. All the computations are performed by an in-house CFD solver, which is used to solve RANS (Reynold Average Navier-Stokes) equations coupled with six degrees-of-freedom solid-body motion equations. The Level Set Method is used to solve the free surface. Verification work on the grid number and time step size has been conducted. The simulation results agree with the experimental results well, which shows that the numerical method is accurate enough. In this paper, several different working conditions are set up, and the effects of the liquid height in the tank, the size of the tank and the wavelength ratio of the incident wave on the ship’s motion are studied. The results show the effect of tank sloshing on the ship’s motion in different working conditions.

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Research on Motion Characteristics and Formation Mechanism of Debris Flow

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.711.388 ◽

2014 ◽

Vol 711 ◽

pp. 388-391

Author(s):

Ji Wei Xu ◽

Ming Dong Zhang ◽

Mao Sheng Zhang

Keyword(s):

Debris Flow ◽

Formation Mechanism ◽

Debris Flows ◽

Catchment Area ◽

Large Scale ◽

Large Range ◽

Extreme Rainfall ◽

Small Catchment ◽

Rainfall Characteristics ◽

Motion Characteristics

On July 9 2013, debris flows occurred around Longchi town with large scale and wide harm, which was a great threat to people's life and property as well as reconstruction work. Debris flow ditch in the surrounding town was studied. This paper focused on loose materials, topography and rainfall characteristics, and explored the formation mechanism of debris flow in Longchi town. The result shows that: a small catchment area in valleys also have the risk of large range of accumulation of debris flow, the debris flow is caused by a lot of loose materials in mountains after earthquake and extreme rainfall. Research results contribute to a better understanding of trigger condition of debris flow after earthquake.

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Effects of Seismic Incident Directionality on Ground Motion Characteristics and Responses of a Single-Mass Bi-Degree-of-Freedom System

International Journal of Structural Stability and Dynamics ◽

10.1142/s0219455421501194 ◽

2021 ◽

pp. 2150119

Author(s):

Jun Gong ◽

Xudong Zhi ◽

Feng Fan ◽

Shizhao Shen ◽

Da Qaio ◽

...

Keyword(s):

Ground Motion ◽

Large Scale ◽

Seismic Analysis ◽

Ground Motions ◽

Propagation Distance ◽

Degree Of Freedom ◽

Different Types ◽

Single Mass ◽

Motion Characteristics ◽

The Impact

To investigate the variability of ground motion characteristics (GMC) with the angle of seismic incidence (ASI) and the impact of seismic incident directionality on structural responses, first, a large-scale database of recorded ground motions was used to analyze the causes of GMC variability due to the seismic incident directionality effect (SIDE). Then a single-mass bi-degree-of-freedom system (SM-BDOF-S) with different types of symmetrical sections was selected to explore the influence mechanism of SIDE on the seismic responses. The results illustrated that the GMC has substantial variability with the ASI, which is independent of the earthquake source, propagation distance, and site condition, and exhibits complex random characteristics. Additionally, a classification method for ground motions is proposed based on this GMC variability to establish a criterion for selecting ground motions in seismic analysis considering the SIDE. Moreover, for an SM-BDOF-S, the response spectral plane is proposed to explain the transition behavior of spectral responses that are very similar among different stiffness ratios, but divergent for different types of ground motions. The influence of SIDE on structures is determined by their stiffness and stiffness ratio in the [Formula: see text]- and [Formula: see text]-directions, as well as the type of ground motion.

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Experimental Study on a Motion of “Underwater Platform” Including Hydro-Elastic Deformation in Waves

Volume 6: Ocean Space Utilization ◽

10.1115/omae2015-41722 ◽

2015 ◽

Author(s):

Motohiko Murai ◽

Ken Haneda ◽

Jun Yamanoi ◽

Yuta Abe

Keyword(s):

Numerical Simulations ◽

Elastic Deformation ◽

Large Scale ◽

Offshore Wind ◽

Offshore Wind Turbine ◽

Wind Condition ◽

Small Motion ◽

Small Water ◽

Motion Characteristics ◽

Plane Area

A new type of floater for floating offshore wind turbine (FOWT) was proposed. The floater, named an “underwater platform”, aims at high economic efficiency of energy generation of floating wind farm. The underwater platform is a large scale submerged structure which has small water plane area and can support several wind turbines. It is expected that the platform has small motion characteristics in waves because of its small water plane area, and it contributes for FOWT to generate energy safety. In this study, the feasibility and usefulness study about the platform was carried out through experiments and numerical simulations. The first experiment was conducted with partial rigid model of the platform to verify the feasibility. From the experiment, it was confirmed that the model has small motion characteristics in waves. The experimental results were compared with numerical simulations of potential theory and they were well matched. Besides, the coupling analysis with aero-hydro dynamics was also carried out and it was confirmed that the stability of the platform was enough in steady wind condition. The second experiment was conducted with elastic body model to study the elastic deformation of the platform in waves. From the experiment, it was confirmed that the deformation is small when the draft was 250mm (50m in the actual model).

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Evaluation of Ground Motion Characteristics of Residential Development Area at Large Scale

Journal of Japan Association for Earthquake Engineering ◽

10.5610/jaee.15.7_100 ◽

2015 ◽

Vol 15 (7) ◽

pp. 7_100-7_113

Author(s):

Toru SEKIGUCHI ◽

Shoichi NAKAI

Keyword(s):

Ground Motion ◽

Large Scale ◽

Residential Development ◽

Development Area ◽

Motion Characteristics

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A Fundamental Study on Motion Characteristics and Cargo Handling Efficiency of the Large-Scale Floating Coal Transshipment Station

Volume 6: Ocean Space Utilization ◽

10.1115/omae2018-77727 ◽

2018 ◽

Author(s):

Hiroaki Eto ◽

Yoh Shikita ◽

Tomoki Ikoma ◽

Koichi Masuda ◽

Hiroaki Kihara

Keyword(s):

Large Scale ◽

Mutual Interference ◽

Response Analysis ◽

Bulk Carrier ◽

Motion Response ◽

Cargo Handling ◽

Wave Drift ◽

Bulk Carriers ◽

Drift Force ◽

Motion Characteristics

This paper describes the motion characteristics and cargo handling efficiency of the Large-Scale Floating Coal Transshipment Station (LFTS). Indonesia is a main country supplying coal in the Asia-Pacific region, it is important to ensure a stable coal supply to Japan. Because the topography of the seabed near East Kalimantan Island, Indonesia’s main coal production area, is shallow, it is difficult for bulk carriers to reach the coast. Therefore, LFTS is proposed, which will be used as a relay base between coal-barging barges from land and bulk carriers offshore. By installing LFTS, improvement of coal transport efficiency is expected. In considering feasibility of the LFTS system, it is important to know the cargo handling operation rate in the target area, LFTS can load 500,000 tons of coal and the draft will fluctuate greatly depending on the loading condition of coal. Therefore, when the draft is shallow, the freeboard becomes large and resonates with long-term component of the wind load and when the draft is deep, the wave force and fluid force including the slowly varying wave drift force affect the fluctuation. Also, LFTS and bulk carrier are large-scale structures, the fluid forces acting on both affect each other, so the influence of hydrodynamic mutual interference between two floating bodies cannot be ignored. In this study, fluid analysis in consideration of the hydrodynamic mutual interference of LFTS system is conducted. And, response analysis of LFTS and a bulk carrier in irregular wave which considered compound external forces such as wave load and slow varying wave drift force, wind load, tidal current was performed. As a result, it was confirmed that the motion response of LFTS was not upset because LFTS was large. Therefore, without considering the motion response of the LFTS, the cargo handling efficiency is calculated from the response analysis results of the bulk carrier and the oceanic condition of the setting sea area. As a result, the cargo handling efficiency is satisfied in the state where bulk carrier is installed leeward of LFTS, and it was confirmed that the LFTS system could be operated satisfactorily if the installation was appropriate.

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Structure and Motion of Severe-Wind-Producing Mesoscale Convective Systems and Derechos in Relation to the Mean Wind

Weather and Forecasting ◽

10.1175/waf-d-16-0060.1 ◽

2017 ◽

Vol 32 (2) ◽

pp. 423-439 ◽

Cited By ~ 6

Author(s):

Matthew A. Campbell ◽

Ariel E. Cohen ◽

Michael C. Coniglio ◽

Andrew R. Dean ◽

Stephen F. Corfidi ◽

...

Keyword(s):

Large Scale ◽

Mean Flow ◽

Convective Systems ◽

Structure And Motion ◽

Mesoscale Convective ◽

The Mean ◽

Wind Events ◽

Motion Characteristics ◽

Definition Of ◽

Convective Vortices

Abstract The goal of this study is to document differences in the convective structure and motion of long-track, severe-wind-producing MCSs from short-track severe-wind-producing MCSs in relation to the mean wind. An ancillary goal is to determine if these differences are large enough that some criterion for MCS motion relative to the mean wind could be used in future definitions of “derechos.” Results confirm past investigations that well-organized MCSs, including those that produce derechos, tend to move faster than the mean wind, exhibiting a significantly larger degree of propagation (component of MCS motion in addition to the component contributed by the mean flow). Furthermore, well-organized systems that produce shorter-track swaths of damaging winds likewise tend to move faster than the mean wind with a significant propagation component along the mean wind. Therefore, propagation in the direction of the mean wind is not necessarily a characteristic that can be used to distinguish derechos from nonderechos. However, there is some indication that long-track damaging wind events that occur without large-scale or persistent bow echoes and mesoscale convective vortices (MCVs) require a strong propagation component along the mean wind direction to become long lived. Overall, however, there does not appear to be enough separation in the motion characteristics among the MCS types to warrant the inclusion of a mean-wind criterion into the definition of a derecho at this time.

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