bluuebunny/crossref_metadata_2025_split huggingface dataset:
Weather Downtime Estimation Using a Simulation Tool
Authors: Mol Arjan , van Goethem Delphine , Smith Timothy 
Published: August 2024

Abstract
Marine operations are heavily influenced by the weather conditions onsite, be it the sea state or other adverse climatic conditions. When the operational limits are breached the works stop and the installation waits for the weather conditions to improve, this is known as weather downtime (WDT). During project preparation, it is essential to accurately quantify the expected downtime when calculating the project budget and schedule. For contractors, the expected WDT is a key input during tender phase of marine installation projects. It determines the most efficient scenario, the project schedule and the choice of equipment, and hence it has a significant impact on the overall budget estimation.
Various methods exist to assess WDT, which differ in the level of detail and complexity that can be considered. The most detailed method is the ‘simulation based on hindcast timeseries’ approach. This paper discusses the in-house developed tool CycleSim, which is one example of a WDT simulation tool. Based on a few example cases, the capabilities of this tool will be demonstrated as well as its added value compared to other methods and tools.
The tool is not only capable of considering complex combinations of basic weather limits (e.g., wind, wave, and current conditions), but it can also deal with more special phenomena such as coupled activities, daylight restrictions, inhibited working periods and flexible waiting windows (i.e., waiting for the tidal current to get below a certain limit). It can not only deliver basic statistical information about the expected project duration for the total offshore installation, including uncertainties (percentiles), but it can also provide planning calendars for each activity of the installation. Finally, it can determine the total expected fuel consumption which can be used to estimate the expected emissions which makes it possible to compare installation methods and choose the most optimal one from a sustainability point of view.
Modeling of Hydroacoustic Noise From Marine Propellers With Tip Vortex Cavitation
Authors: Cheng Zhi , Kashyap Suraj , Smoker Brendan , Burella Giorgio , Jaiman Rajeev 
Published: August 2024

Abstract
Due to growing marine ecological concerns, there is an acute industrial need to significantly reduce the underwater radiated noise (URN) from marine propellers during ship operations. In this regard, high-fidelity fluid flow and hydroacoustic models are required for understanding the propeller noise generation and propagation in the ocean environment. Using high-fidelity CFD modeling, the present work aims to study the cavitating turbulent flow of a full-scale marine propeller and explore the physical mechanism underpinning the underwater radiated noise. We employ the standard dynamic large eddy simulation for the turbulent wake flow and the Schnerr-Sauer cavitation model, while the Ffowcs-Williams-Hawkings acoustic analogy is considered for the hydroacoustic modeling. For the current investigation, we consider a well-known Potsdam Propeller Test Case to analyze the turbulent cavitating flow and the associated hydroacoustic emissions. To begin, the modeling framework is validated using the available experimental data, and distinctive double-helical tip vortex cavitation and its qualitative patterns along the vortex trajectory are captured. In comparison to the non-cavitating condition, the pressure distribution on the propeller surface is more disordered for the cavitating condition, which is further reflected by a relatively stronger power of both low-frequency tonal peaks and high-frequency broadband components in the spectrum of thrust generation. Specifically, the generation of cavitation leads to the enhancement of the monopole noise source and the breakdown of cavitation bubbles as well as vortex structures in the turbulent wake. Furthermore, the tonal noise with the frequency corresponding to the harmonics of blade passing frequency is also enhanced. Generally speaking, the generation of cavitation structures enhances the hydroacoustics energy of URN at all orientations, especially in the downstream direction with sound pressure level increasing up to 20 dB.
Mooring Optimization of Floating Offshore Wind Turbines Using Genetic Algorithm
Authors: do Vale Machado Lucas , Shadman Milad , Amiri Mojtaba Maali , Estefen Segen Farid 
Published: August 2024

Abstract
Most global wind resources are found in water depths exceeding 60 meters, where using bottom-mounted structures is challenging and costly. Thus, increased the studies on floating offshore wind turbine (FOWT) solutions characterized by complex dynamics between the floating structures and turbines. Nowadays, one key challenge is designing optimum mooring arrangements for large-scale FOWT.
A meta-heuristic solution is recommended to solve a complex optimization problem, such as the mooring arrangement of a floating wind turbine. Among these, the Evolutionary Algorithms (EA) use mechanisms inspired by biological evolution. Genetic Algorithm (GA) is a multi-objective search and optimization algorithm based on the concept of Darwin’s theory of evolution, and it belongs to the class of Evolutionary Algorithms. It combines the idea of survival of the fittest with randomized information exchange.
Based on the literature, multi-objective optimization algorithms, such as the GA, are commonly used with hydrostatic and frequency-domain models, which are less accurate than a time-domain model for optimization purposes of FOWT.
This work addresses the optimization of the mooring system of a FOWT using time-domain simulations in OpenFAST. An in-house code is developed to handle calculations on OpenFAST and apply GA to find the optimal mooring arrangements for specific design variables meeting predefined multi-objectives, respecting all specific constraints for the FOWT. Finally, the optimized arrangements are checked against Ultimate Limit State (ULS) and Accidental Limit State (ALS), performed for the mooring system in damaged condition.
The developed optimization process is applied to the UMaine VolturnUS-S semisubmersible platform to maximize power quality and minimize the costs of the lines.
Numerical Study on the Characteristics of Bow-Flare and Stern Asymmetric Slamming for Container Ships
Authors: Lu Lin , Ren Huilong , Li Hui 
Published: August 2024

Abstract
The large bow flare and flat stern of container ships can result in a significant slamming phenomenon. Asymmetric slamming often occurs in oblique waves. The slamming can lead to ship vibration, reduced speed, and direct structural damage in severe cases. However, the prediction of slamming loads remains a challenge due to the highly nonlinear characteristics of the free surface and the physical surface conditions. This paper aims to provide a deeper analysis of the mechanisms of the oblique water entry process of the bow and stern of container ships. A numerical model of the two dimensional (2D) section is established using the open-source software OpenFOAM, incorporating the Volume of Fluid (VOF) method to solve the water-air phase flow. The free surface flow, slamming forces and the distribution of slamming pressures along the section were obtained. The numerical model is validated against available experimental data from the literature and the accuracy of the algorithm is discussed. The differences in slamming characteristics resulting from various shape features of the bow and stern is explored. Additionally. the comprehensive effects of geometric asymmetry during water entry are investigated by systematically altering the section’s roll angle. This study is expected to provide a reliable algorithmic framework for coupling slamming loads with the ship motion in the future.
An Experimental Study of Roll Damping Using a Pendulum-Based System
Authors: Xi Kemeng , Milne Ian , Draper Scott , Chen Lifen 
Published: August 2024

Abstract
A hull-pendulum system is introduced to investigate the roll damping of a hull through roll decay. Compared to conventional roll decay tests, this method can reduce the decay of the KC number (roll amplitude) and more conveniently allows for a range of oscillatory frequencies to be investigated. Further, the setup allows for roll damping experiments with low mechanical friction and at low cost. The study primarily focuses on flow separation and vortex shedding. Two types of sharp bilges were investigated: a square bilge and a round bilge equipped with a bilge keel. The results demonstrate that, in most of the scenarios studied, the roll damping coefficient is proportional to the roll amplitude, which aligns with the assumption and prediction of the Ikeda method. However, for bilge keel configurations, the roll damping coefficient decreases rapidly at ϕ ≤ 2°. These findings are consistent with the prediction of isolated edge theory that the roll damping coefficient is proportional to KC2/3 in the case of the bilge keel with ϕ ≤ 2°. For ϕ &gt; 2°, the isolated edge theory suggests that the damping coefficient, effectively reverting to that of a square edge, should be proportional to KC, as corroborated by experimental observations.
Analysis of Implosion Protection Effect of Ceramic and Titanium Alloy Hollow Spheres Wound With Carbon Fiber
Authors: Zhang Xinyu , Zhao Min , Ge Tong 
Published: August 2024

Abstract
As an important part of deep-sea submersibles, once a catastrophic implosion occurs, the pressure-resistant structure will pose a huge threat to the vitality of deep-sea equipment. Therefore, it is necessary to conduct relevant research on implosion protection. In this work, we selected ceramic and titanium alloy hollow spheres as deep-sea flotation devices, and formed a composite pressure-resistant structure with both lightweight and implosion protection advantages by winding carbon fiber outside them. Based on the open-source solver OpenRadioss, the arbitrary Lagrangian-Eulerian method is used to simulate the implosion process of composite hollow spheres. Firstly, the feasibility of the numerical method is verified by comparing with the relevant experiment. Secondly, the response analysis of the two composite hollow spheres is carried out. The 3D Hashin criterion, the maximum principal stress criterion and the Johnson-Cook failure criterion are used to describe the failure of carbon fiber reinforced polymer (CFRP), ceramic and titanium alloy respectively. By comparing the flow field response and structural collapse form, the influence of outer winding carbon fiber on the implosion characteristics of ceramic brittle material hollow spheres and titanium alloy ductile material hollow spheres is discussed. The failure modes of hollow spheres with different lining materials are summarized, and the advantages of this scheme in lightweight and implosion protection are highlighted. In summary, this work not only clarifies the mechanism of implosion, analyzes the structural response, and proposes implosion protection measures, but also provides a reference for the material selection and design of deep-sea equipment structures.
Research on a Fast Resistance Performance Prediction Method for SUBOFF Model Based on Physics-Informed Neural Networks (PINNs)
Authors: Wu Yuliang , Han Fenglei , Peng Xiao , Gao Liangtian , Zhao Yiming , Zhang Jiawei 
Published: August 2024

Abstract
Physics-Informed Neural Networks (PINNs) represent a novel intelligent algorithm for solving partial differential equations (PDEs), which has been partially validated in solving Navier-Stokes equations. However, numerous challenges remain in the application of PINNs to the calculation of hydrodynamic performance of ships.
This paper utilizes discrete solutions of the Navier-Stokes (N-S) equations obtained via the Finite Volume Method (FVM) and Reynolds Averaged Navier-Stokes (RANS) approach of the CFD method for training PINNs to directly solve flow field information. This approach achieves a solution with approximate accuracy to that based on the CFD method, but with significantly reduced time consumption. The development of this algorithm could offer a novel perspective for calculating the hydrodynamic performance of ships.
The study focuses on the DARPA SUBOFF-B model, using field information obtained at specific speeds through the CFD method, including pressure and velocity fields, as the training set to train the neural parameters within PINNs. This enables the PINNs model to predict the flow field information around the hull and calculate the hull resistance through integration. The results predicted by the PINNs method are compared and analyzed against those calculated via the CFD method, Shows the comparison of the predicted results of the hull surface pressure field, as well as the relative error of the predicted total resistance., thereby proving the feasibility of the method.
A Journey Towards Safer and Faster Drilling: Real-Time Advisory With Digital Twins and AI
Authors: Gu Chunwei , Xu Tong , Lye Jen , Ødegård Sven Inge , Cao Jie 
Published: August 2024

Abstract
The oil and gas industry has undergone remarkable advancements in embracing digital transformation, revolutionizing its operations, and unlocking many new opportunities. This paper presents the journey of digital transformation toward achieving safer and faster drilling operations within CNOOC. Specifically, the focus will be on implementing drilling advisory systems and their diverse applications in enhancing efficiency, cost reduction, safety improvement, and operational optimization.
The real-time drilling advisory system relies on cutting-edge technologies such as digital twins and artificial intelligence (AI) to operate effectively. A drilling digital twin is a digital replica of the physical well throughout the entire drilling life cycle. Its functionality stems from dynamic hydraulic, thermal, and mechanical modelling that accurately simulates drilling operations. Driven by real-time data, the digital twin facilitates automated monitoring, forward-looking analysis, and predictive insights. To create diagnostics of drilling events in advance, the advisory system employs model-based reasoning, an AI inference method. Continuously updated with real-time data streamed from the rig, the digital twin promptly generates diagnostic messages, identifying risks or issuing warnings based on predictive analysis and forecasting. In conclusion, the real-time advisory system empowers drilling engineering by enabling enhanced operational efficiency, safety, and sustainability, while driving significant cost reductions and fostering opportunities for growth and innovation.
Combined EFD and CFD Approach for Full Scale Ship Resistance Predictions Using the Form Factor
Authors: Quintuña María , Horn Peter , Zhang Junheng , Sprenger Florian 
Published: August 2024

Abstract
In this study, a comparison of the experimental full scale ship resistance extrapolation procedure using the ITTC’78 power prediction method with a newly proposed hybrid EFD/CFD approach has been performed for two benchmark ship hull geometries. For both hulls, resistance tests have been performed in the towing tank of HSVA at model scale. From these tests, experimental form factors have been determined according to Prohaska’s approach. In addition, CFD simulations have been performed to determine a new numerical flat plate friction line as well as the frictional resistance for both hulls by double body CFD simulations in model and full scale. Based on these simulations, numerical form factors according to Hughes have been derived. Two different turbulence models, the k-ω standard and the k-ω SST, have been used to obtain the flat plate frictional resistance curve. It has been found that the mean difference between the numerical form factors obtained for model and full scale CFD simulations is 10.4% using the ITTC’57 correlation line. When using the newly established numerical friction line based on the k-ω SST model, this mean difference is reduced to mean 6.4%. Based on the results, full scale resistance predictions were performed based on the different form factors that have been derived following the ITTC’78 method. Since no data from sea trials is available, the full scale resistance predictions for the two ship hulls were compared with the results of full scale CFD simulations. It was found that the extrapolation based on the form factor derived from the numerical friction line using the k-ω SST shows a 3.1% deviation from the full scale CFD results, while a deviation of 7.1% was observed for the form factor based on the ITTC’57 line.
Numerical Simulation of Ascending Motion of Polymetallic Nodules for Hydraulic Lifting of Vertical Pipes
Authors: Liu Yajiao , Dou Peilin , Li Xiu 
Published: August 2024

Abstract
Deep-sea polymetallic nodule hydraulic lifting program belongs to the particle fluid complex system of solid-liquid two-phase flow problems, most of the previous research for low-density, small-sized particles, for high-density, large-sized particles of the research is mostly carried out in the net water free-fall problem .In this paper, the solid-liquid two-phase flow of seawater with polymetallic nodules was numerically calculated using the CFD-DEM semi-analytical method in the context of deep-sea mining polymetallic combined with hydraulic lifting. The effect on the particle rise process was investigated for several cases, such as the particle fluid density ratio of 1:2, different pipe diameters with particle size ratios of (2∼10), different pipe Reynolds numbers (400∼2000; lifting velocities of 2∼10m/s), and different initial positions of the particles. The accuracy of the computational model is also verified by comparing the infinite-boundary free-fall experiments with the results of the literature by Lei Liu and Horowitz M. The results are summarized as follows. Through numerical simulation, five subdivided types of particle ascent trajectories were obtained; Different Reynolds numbers and particle size ratios also have an impact on the upward trend of particles, while changes in initial position have little effect on the upward velocity of particles.
Evaluation of Mooring Line Degradation in Floating Offshore Wind Turbines: A Comprehensive Analysis of Corrosion and Fatigue Under Environmental Impacts
Authors: Beer Theresa Marie , Karpenko Olena , Collu Maurizio , Coraddu Andrea 
Published: August 2024

Abstract
As the demand for renewable energy grows, floating offshore wind turbines have become crucial, especially in deep water areas where traditional structures are impractical. These turbines need station keeping systems, which often consist in catenary mooring lines, making their durability vital against extreme weather conditions. While direct monitoring of these lines would be preferable, it is often unpractical due to high costs and maintenance. This research presents a new method to evaluate the degradation of mooring lines. The study investigates fatigue and corrosion behavior along the mooring lines by simulating environmental impacts, considering varied forces and weather patterns. Considering seawater’s oxygen and temperature, a distinct corrosion model is merged with fatigue performance predictions based on DNV standards. Mooring line loading conditions derived from environmental factors are then incorporated into a finite element model, assessing various load cases and corrosion’s role in line degradation. This comprehensive model examines the combined effects of corrosion (in particular, pitting corrosion) and fatigue, including hydrostatic pressure and out-of-plane bending on the performance of the mooring line chain in the offshore environment. The methodology’s validation relies on previous research and mooring line operational data.
The Bearing Capacity of Torpedo Anchor in Clay Under Inclined Loading of Mooring Chain
Authors: Tang Chao , Wu Xiaoni , Shu Jian , Chen Jinjian , Wang Teng 
Published: August 2024

Abstract
Torpedo anchors represent a promisingly innovative anchorage foundation for deep water applications due to their efficient and economical installation. During installation, a significant length of mooring chain was embedded into the seabed alongside the torpedo anchor. This interaction between the chain and the soil alters the strength characteristics of the clay, and also affect the loading angle at the padeye during pullout. As a result, the bearing capacity of the torpedo anchor is influenced by the movement of the chain. However, existing numerical studies lack a comprehensive understanding of the pullout performance of torpedo anchors, particularly in considering the presence of mooring chains. This study endeavors to investigate the pullout capacity of torpedo anchors in clay, accounting for the effect of the mooring chain attached to the padeye, utilizing the large deformation finite element method (LDFE). The elastic-perfectly plastic material model, adhering to the modified Tresca yield criterion, was employed. Verification of the model’s accuracy and effectiveness was conducted through centrifuge test results. The influence of the mooring chain and loading angle on the pullout capacity were investigated. The findings indicate that the discrepancy in the bearing capacity of torpedo anchors, with and without considering the mooring chain, increases from 3% to 38.4% as the loading angle rises from 0° to 75°. Conversely, for vertical loading, the difference decreases to 7%. Based on the numerical analysis, normalized V-H envelopes were provided. This work contributes valuable insights into the capacity of torpedo anchors.
Time-Harmonic Ship Waves From the Perspective of an Earth-Fixed Observer
Authors: Chen Xiaobo , Liang Hui 
Published: August 2024

Abstract
Time-harmonic flows around a ship advancing in waves are usually described in the coordinate system moving with the ship’s average speed. Within this moving reference system, detailed descriptions of ship waves have been made in many previous studies. Recent works in [1, 2] revealed that essential physical features such as different wave systems and their wavelengths, cusp angles, phase, and group velocities, are directly related to wavenumber curves determined by the dispersion relation on the mathematical Fourier plane. Insightful physical results have been achieved and applied in developing numerical tools to predict ship seakeeping. However, the description of time-harmonic ship waves in the Earth-fixed coordinate system is missing although a few studies exist on steady ship waves like that in [3, 4] It is not trivial to transform results in the moving coordinate system to the fixed coordinate system. Much caution is needed to obtain consistently the phase and group velocities which are closely associated with wave crestlines. In the present study, after summarising classical results in the moving coordinate system, detailed analyses of time-harmonic ship waves in the Earth-fixed coordinate system are presented with numerical illustrations. The results obtained in both coordinate systems are believed to be useful in the prediction of ambient waves due to the passage of ships.