bluuebunny/crossref_metadata_2025_split huggingface dataset:
Research on the Influences of Broken Ice Parameters on Maneuverable Forces of Ice-Going Ship Oblique Sailing
Authors: Xuan Shenyu , Zhan Chengsheng , Liu Zuyuan , He Binfeng , Zhao Qiaosheng , Guo Wei 
Published: October 2021

Abstract
The broken ice is one of the most common ice conditions for ice-going ships, and the research of ship maneuvering movement in broken ice field can improve sailing safety. In this paper, the discrete element method (DEM) was adopted to study the maneuverable forces, including resistance and transverse force, of ice-going ship oblique sailing in broken ice fields. First, the Araon model tests data of Korea Institute of Ocean Science & Technology (KIOST) was used to verify the ice resistance of direct sailing under different ice sizes and model speeds, and the numerical results are in good agreement with the test results. Second, the influences of broken ice parameters (including concentration, thickness, and shape) on ship-ice interaction and maneuverable forces distribution were researched. The maneuverable forces on the ice-going ships are mainly from the ship-ice interaction. The time history curves of maneuverable forces were analyzed from the average value of maneuverable forces, the average value of peak maneuverable forces, and the number of peaks. Besides, the parameters of broken ice have a heavy influence on the movement of broken ice around the hull, such as accumulating and sliding. The analysis of the broken ice movement contributes to understanding the influences of broken ice parameters on ice-going ships.
Bilinear Fatigue Performance of Composite Marine Risers in Deep Offshore Fields Due to Vortex Induced Vibrations
Authors: Khan Rizwan Ahmad , Ahmad Suhail 
Published: October 2021

Abstract
Risers are an integral part of an offshore oil and gas exploration structures, and that they are prone to vortex-induced vibration (VIV). Although several studies are conducted to analyze the VIV characteristics of risers, the results of amalgamation of multiple parameters and also the relative significance of every parameter on the risers’ VIV characteristics have seldom been considered. Vortex elicited vibration is one of the main causes of the fatigue damage of the riser. In deep sea atmosphere currents sometimes vary in magnitude and direction with depth, thereby causing the likelihood of exciting multiple modes of the riser vibration because of VIV. Vortex elicited vibration analysis has been carried out of a long marine riser for different probable sea locations. To boost the understanding of deepwater environments, the behavior of a composite riser under these forces is investigated. 3D nonlinear dynamic analysis of riser is obtained in time domain using finite part software package ABAQUS/Aqua. The response histories thus obtained are utilized for fatigue safety analyses of the riser. Uncertainty modeling, particularly of crack growth parameters, is undertaken by means of the bi-linear crack growth relationship. Results concerning fatigue safety and crack size evolution are given using Monte Carlo Simulation. The bi-linear crack growth models are found to result in to higher fatigue life estimation. Sensitivity behavior pertinent to limit state adopted has also been investigated.
Numerical Simulations of Sinusoidally Oscillating Cross-Flow Around a Circular Cylinder
Authors: Gamaleldin Muhannad W. , Babanin Alexander V. 
Published: October 2021

Abstract
A numerical study is conducted to investigate a sinusoidal oscillatory cross-flow around a smooth circular cylinder. A numerical model based on the Reynolds-averaged Navier-Stokes (RANS) equations with the k-ω Shear Stress Transport (SST) turbulence model is implemented, using the open source C++ package OpenFOAM®. The study focuses on the level of confidence in using two-dimensional numerical simulations for the predictions of the inherent transient behaviour of the highly nonlinear hydrodynamic induced loads. Simulations are conducted for two values of Keulegan-Carpenter (KC) number corresponding to inertia-dominated and drag-inertia regimes, for a fixed value of the frequency parameter β. Boundary layer separation structures and their temporal evolution are investigated and visualized by means of turbulence kinetic energy contours. Moreover, inline forces inertia and drag coefficients of Morison loads decomposition are found and validated against previous experimental results in literature. Finally, transverse forces and their spectral content is investigated and validated. The study shows that the magnitude and frequency of the unsteady hydrodynamic induced forces coefficients are well reproduced and are in a very good agreement with the experimental observations.
Coupling of Potential Flow and CFD Model for Fluid and Structure Interactions
Authors: Xu Haihua , Zhang Yali , Santo Harrif , Chua Kie Hian , Law Yun Zhi , Chan Eng Soon 
Published: October 2021

Abstract
Computational Fluid Dynamics (CFD) tools are widely used to simulate wave and structure interactions in marine & offshore industry. However, conventional CFD tools require significant computational resources. This is largely due to the requirement of large computational domain to ensure adequate development of nonlinear wave evolutions as well as to avoid boundary effects resulting from wave interacting with any fixed or floating structures in the domain. Furthermore, very fine mesh elements are required to avoid excessive numerical dissipation during wave propagation. All of these factors will significantly increase the computational costs, resulting in the conventional CFD approaches being impractical for simulations of wave-structure interactions over a long duration.
In this paper, a coupled potential flow and CFD model is developed to reduce the simulation cost. The model decomposes the simulation domain into far-field and near-field region. Wave propagation in the far-field region is simulated by a potential flow solver (High-Order Spectral or HOS method), while the wave-structure interactions in the near-field region are simulated by a fully nonlinear, viscous, and two-phase CFD solver (Star-CCM+). A forcing zone is distributed between the two regions to blend the computational outputs from the potential flow into the CFD solvers. The coupling algorithm has been developed to improve the accuracy and efficiency.
The coupled solver is applied to simulate two cases, namely regular wave propagation, and regular wave interaction with a vertical cylinder. Finally, a simulation of a 3D wave encountering an FPSO (Floating Production Storage and Offloading) is presented.
Ship Damage Stability Approval Document Generation by a Amonte Carlo Method
Authors: Krüger Stefan , Aschenberg Katja 
Published: October 2021

Abstract
The revised SOLAS 2020 damage stability regulations have a strong impact on possible future ship designs. To cope with these requirements, damage stability investigations must become a central part of the initial design phase, and many internal subdivision concepts need to be investigated. Unfortunately, if damage stability calculations are performed in the classical way, they are very time consuming with respect to modelling and computational time. This fact has impeded the consequent subdivision optimization in the past. Therefore, a simulation procedure for damage stability problems was developed which treats damage stability as a stochastic process which was modeled by a Monte Carlo simulation. If statistical damage distributions are once known, the Monte Carlo simulation delivers a population of damages which can be automatically related to certain damage cases. These damage cases can then be investigated with respect to their survivability. Applying this principle to damage stability problems reduces the computational effort drastically where at the same time no more manual modelling is required. This development does especially support the initial design phase of the compartmentation and leads to a safer and more efficient design. If this very efficient simulation principle shall now also be used after the initial design phase for the generation of approval documents, additional information needs to be generated by the simulation method which is not directly obtained during the simulation: This includes detailed individual probabilities in all three directions and the integration of all damage cases into predefined damage zones. This results in fact in a kind of reverse engineering of the manual damage stability process to automatically obtain this required information. It can be demonstrated that the time to obtain the final documents for the damage stability approval can be drastically reduced by implementing this principle.
Comparing Numerical and Analytical Solutions of Solitary Water Waves Over Finite and Variable Depth
Authors: Hallak Thiago S. , Islam Hafizul , Mohapatra Sarat Chandra , Guedes Soares C. 
Published: October 2021

Abstract
In this paper, three methods are used in order to obtain the solution for the propagation of water solitons over finite and variable depth. First, the exact analytical solitary wave solutions of the one-dimensional non-linear Boussinesq equations under shallow water condition are described for constant and variable depth. Second, the three-dimensional Fully Non-linear Potential Flow code OceanWave3D is used in order to obtain the numerical solutions for the solitary waves’ propagation over same depth ranges, providing robust solutions for the potential flow problem. Third, Computational Fluid Dynamics’ tool OpenFOAM is used in order to obtain the viscous solution for the same problem, however, without the accounts of turbulence models. The free-surface profiles are drawn and compared; and the stability of the numerical solutions are assessed. Since the approximations of Boussinesq-type equations depend mainly on the orders of magnitude of amplitude and depth, the numerical-analytical comparison will draw the limits for the validity of the analytical solutions. On the other hand, the comparison will provide the limits where viscous effects start playing an important role, whereas the CFD simulations predict the occurrence of wave breaking. These benchmark cases are compared with past references. After all, results regarding the same phenomena have been described in the literature according to, e.g. Fully Non-linear Boussinesq Models, and Fully Nonlinear Potential Flow schemes solved by Boundary Element Methods. Last but not least, the open source Fully Non-linear Potential Flow code is used in order to provide the potential flow solution for some extra cases of water soliton propagation, in order to capture the trends in weak shoaling scenarios.
Analyzing the Fluid Mechanics of the Dump Bailing Method in the Plug and Abandonment of Oil and Gas Wells
Authors: Akbari Soheil , Taghavi Seyed Mohammad 
Published: October 2021

Abstract
Plug and abandonment (P&A) of oil and gas wells is receiving an increased attention. The P&A operation is performed by placing a barrier, such as a cement plug to avoid reservoir fluids migration toward aquifers. To fulfill these requirements, the desired cement plug should be placed in the wellbore with minimum mixing with the in-situ fluid. A rigless way for placing cement slurry in the wellbore is through the dump bailing method, in which a relatively small amount of cement slurry is injected on a mechanical barrier inside the well to replace the in-situ wellbore fluids (mostly fresh water). The dynamics of the fluid placement is governed by several parameters, such as the flow and geometry parameters, and the fluid properties.
In this study, we analyze the fluid mechanics of the dump bailing method, via experimentally investigating the effects of the viscosity ratio between the replacing and replaced fluids in the process. The viscosities of the fluids involved have significant effects on the mixing and placement flow quality. In our experiments, the fluid placement is carried out in a near-vertical closed-end pipe (i.e. representative of the well casing) to replace an in-situ light fluid. The two fluids are considered to be miscible, and they have a fixed density difference. Our results show that the most efficient placement happens with the injection of the higher viscous fluid. The outcomes of this study can be used for improving the cementing processes in the dump-bailing method of P&A operations.
Experimental Study on the Stability Performance and Turning Motion of Multi-Connection VAWT
Authors: Iwamatsu Saika , Nihei Yasunori , Iijima Kazuhiro , Ikoma Tomoki , Komori Tomoki 
Published: October 2021

Abstract
In this study, a series of dedicated water tank tests were conducted in wind and waves to investigate the stability performance and turning motion of Floating Offshore Wind Turbine (FOWT) equipped with two vertical axis wind turbines (VAWT). The FOWT targeted in this study is called Multi-connection VAWT, which is a new type of FOWT moored by Single-Point-Mooring (SPM) system. We designed and manufactured two types of semi-submersible floating bodies. One is a type in which VAWTs are mounted in two places of a right-angled isosceles triangle (Type-A) on a single floater, and the other is two independent units equipped with VAWTs on two separate floaters centered on a moored body. This is a type in which two semi-submersible floating bodies are lined up in a straight line (Type-B). The experimental conditions were determined by scaling down to 1/100 using Froude’s scaling law based on a wind thrust load of 320 kN (rated wind speed of 12 m/s) assuming an actual machine. In the free yawing test in waves, Type-A turned downwards, while Type-B was barely affected by the waves. Furthermore, in the free yawing test in wind, both Type-A and Type-B turned leeward and stabilized at a final point where the wind load was balanced.
Prediction of Nonlinear Acceleration Response of a Large Container Ship and the Validation of Excessive Acceleration Failure Mode
Authors: Duan Fei , Ma Ning , Gu Xiechong , Zhou Yaohua , Shangming Wang 
Published: October 2021

Abstract
The excessive acceleration is one of five stability failure modes for intact stability being discussed at IMO. The excessive acceleration usually occurs in shallow draft state, under which the ship is prone to large nonlinear rolling motion. Therefore, the accurate prediction and evaluation of the acceleration response are required in ship intact stability analysis. This paper proposes a 5-DOF model in time domain to calculate the nonlinear acceleration response of a large container ship. The nonlinear restoring force and wave exciting forces (F-K force) are calculated through pressure integration on instantaneous wetted surfaces. A model test has been carried out to verify the prediction method of ship nonlinear acceleration response in the regular and irregular waves. It turns out the ship nonlinear acceleration response in regular and irregular waves obtained by the nonlinear time domain simulation agrees well with the experimental results. The vulnerability criteria for excessive acceleration are also validated by numerical and experimental results. In addition, the influence factor of ship lateral acceleration is studied. The results show that the prediction accuracy of 5-DOF model is acceptable. However, the accuracy needs to be improved for the condition of short wavelength. The influence of angular velocity can be ignored.
Real-Time Simulation of Hull Structure Using Finite Element in Virtual Reality Applications
Authors: Li Chuntong , Wei Naikun , Luo Xiaomeng , Lv Jianjun , Yang Xuelian , Wang Deyu 
Published: October 2021

Abstract
Visualization post-processing has become the primary means of awareness and understanding of CAE data intuitively and vividly. Visual analysis can help designers extract meaningful features and results from the complex data quickly and efficiently through intuitive visual images. Virtual reality (VR) -based simulation system can provide experience for the decision-makers and inexperienced workers. We propose a novel solution for real-time Finite Element Analysis (FEA) calculation between wave and hull structure. Firstly, an appropriate CAE system with all the FEA results of the hull is established in a single database. Secondly, based on the Unity 3d platform, effective data transmission technology and three-dimensional virtual models are constructed to achieve an immersive interactive experience. Finally, the third important player is hardware, making the Virtual Reality navigation become possible in many different environments. This paper briefly describes the features of this system. The proposed system employs a distributed simulation framework to realize real-time virtual simulation and human-computer interaction (HCI) of hull structures based on the Finite Element (FE) calculations. In addition, the applicability and the accuracy of the proposed virtual simulation method have also been verified by conducting a case study.
Optimization of Depressurization and Hot Water Injection Development for Class III Offshore Hydrate Reservoirs Based on Particle Swarm Optimization
Authors: Bai Yajie , Hou Jian 
Published: October 2021

Abstract
Based on the basic geological parameters of hydrate reservoir at SH7 station in Shenhu sea area of South China Sea, a numerical simulation model of heterogeneous Class III hydrate reservoir is established. Combining the particle swarm optimization with the numerical simulation of gas hydrate reservoir, taking net energy as objective function, an optimization method for the production parameters of Class III hydrate reservoir by depressurization and thermal stimulation is established. After the established optimization model reaches convergence, the net energy of the optimal scheme is increased by 10.976% compared with the initial scheme, which indicates that the development effect can be effectively improved by using particle swarm optimization method to optimize the development parameters of hydrate reservoir. Reservoir heterogeneity has a great impact on the development effect. Injection wells in low permeability area should inject more heat to stimulate hydrate decomposition, and the corresponding gas production rate in this area is small. The establishment of production parameter optimization method of Class III hydrate reservoir by depressurization and thermal stimulation can improve the recovery efficiency, reduce the energy consumption and promote the commercial exploitation process of the offshore hydrate reservoirs.
Parametric Evaluation of Stress Concentration Factor (SCF) at Brace – Chord Intersection of a Ring Stiffened Tubular Joint
Authors: Sai Krishna G. Chandra , Nallayarasu S. 
Published: October 2021

Abstract
Tubular joints are common in offshore framed structures such as jackets. These joints are subjected to fatigue due to cyclic loads from waves. Stress concentration factor plays a major role in the estimation of fatigue life. Studies have been carried out in the past on stress concentration factors for these joints. However, literature on ring stiffened joints is limited. In the present study, numerical simulations have been carried out on ring stiffened tubular joints, especially the T joints, subjected to axial tension load using finite element method in linear analysis using ABAQUS software. A solid type 20-node quadratic brick element (C3D20R) has been used in the study. Stresses in hotspot locations at brace/chord intersection, ring/chord intersection and ring inner edge are examined. The numerical model has been validated using published experimental data and Lloyd’s register recommendations. Further parametric study has been carried out with 20 models, which includes geometric parameters of ring stiffener such as width of stiffener, thickness of stiffener and spacing between the ring stiffeners. The results of parametric study show a significant reduction of SCF at saddle location by placing ring stiffeners in unstiffened T joint. A set of new parametric equations are developed to calculate SCF for ring stiffened T joint at saddle location for axial tensile load.
Investigation of Model Configuration Parameters for Stick-Slip Modeling
Authors: Wiktorski Ekaterina , Sui Dan 
Published: October 2021

Abstract
Stick-slip vibrations modeling is an important topic within drillstring dynamics. Thus, a number of mathematical models has been suggested to describe behavior of drillstrings under torsional. Most of the models take similar approach with regard to, for instance, drillstring discretization, definition of external forces and velocity-weakening effect.
Commonly, research papers focus on the models’ core — mathematical expressions that describe stick-slip oscillations and inherent to it negative damping. The results are usually presented in terms of downhole rotational velocity or displacement and reaction forces at various surface rotational velocities and applied external forces. However, little attention is paid to discussion and justification of selected model configuration, which includes definition of the following 1) total simulation time, time step, number of masses/elements, etc., 2) initial conditions and boundary conditions, and 3) numerical solver to obtain solution in time. This paper reviews commonly used configurations for stick-slip vibrations modeling and discusses selection criteria provided in the references. It also presents case studies to evaluate effect of the above-mentioned configuration properties on simulations outcome. A simple in-house 1DOF torsional dynamics model was used for that purpose, where one explicit and one implicit numerical solvers were applied to obtain solution in time.
Three case studies are presented, which compare performance of two numerical solvers with respect to convergence and stability. The results from the case studies show, for example, that applied explicit numerical solver (Central Difference Method) introduces numerical damping, while implicit solver (Newton-Raphson Method) does not. Central Difference Method provides convergence when initial force is applied, while damping function has to be defined in case of Newmark-Raphson method to obtain convergence. Stability of the explicit numerical solver is determined by the time step, while selected implicit solver is unconditionally stable. A reasonably small time step has to be selected though to improve the accuracy of the results.
Presented literature review and outcome from the case studies can be used by researchers within this area to select suitable configuration parameters for their models and critically evaluate the outputs. In addition, presented results have application in automated drilling where configuration parameters and calibration factors are updated in real time by control algorithms for continuous modeling of drillstring state with regard to stickslip. Understanding the effects of mentioned properties on system dynamics helps to select suitable combination of operational parameters to stabilize the drillstring.