bluuebunny/crossref_metadata_2025_split huggingface dataset:
On the Structural Analysis of Icebreakers Due to Ramming of First-Year Ice Ridges
Authors: Zhao Weidong , Johan Leira Bernt , Vilhelm Høyland Knut , Kim Ekaterina , Feng Guoqing , Chen Zhanyang , Gui Hongbin 
Published: October 2022

Abstract
Sea ice ridges, formed by compression or shear in the ice cover, bring additional challenges to the structural safety of icebreakers navigating in polar regions. The purpose of this work is to carry out the structural analysis of an icebreaker during ramming of first-year ice ridges. A heavy icebreaker is chosen for the analysis, and the geometrical and physical properties of the ice ridge are determined based on empirical data. The ice ridge is modeled by solid elements deploying the continuous surface cap model (CSCM) with different materials’ parameters for the consolidated part and the unconsolidated part. Based on the numerical simulations of the ship-ridge interactions, the local ice-induced pressure on the hull shell is obtained. Subsequently, the local ice pressure is applied to local deformable sub-structural models of the heavy icebreaker. Subsequently, the ice-induced structural responses of the local sub-structural models are evaluated. Furthermore, the effect of model parameter settings related to the ice ridge on local ice pressures and structural responses are analyzed. Finally, the structural responses of the icebreaker navigating at the ship speed limit is also discussed.
A Semi-Analytical Methodology to Assess the Dynamic Elastic Response of a Monopile Offshore Wind Turbine Subjected to Low-Energy Ship Impacts
Authors: Ladeira Icaro , Le Sourne Hervé , Moran Jonathan , Salazar Priscilla 
Published: October 2022

Abstract
Low-energy impacts between ships and offshore wind turbines (OWT) can occur during maintenance operations, when service vessels need to approach the turbine at low speeds. While this type of accident might not result in significant permanent damage of the tower or the foundation, the whipping elastic response of the overall structure can induce high accelerations at the rotor-nacelle assembly (RNA), where sensitive subcomponents such as the generator, bearings and gearbox are contained.
This study presents a two-step methodology to quickly assess the whipping elastic response of a monopile OWT subjected to a low-energy ship impact. The first step consists of modelling the monopile as a reduced set of Euler-Bernoulli beams with different cross-sections and a tip lumped mass representing the RNA. A semi-analytical framework is used to derive closed-form expressions to calculate natural frequencies and mode shapes of the beam assembly. Once these properties are obtained, the modal superposition method is applied to calculate the monopile’s response to a pre-defined collision force. Validation of this semi-analytical methodology is performed using the nonlinear FEM code LS-DYNA.
The proposed method is intended for pre-design stages, when risk assessments are performed and a large number of collision simulations is required. In this case, fast calculation tools are generally more suitable than FEM, allowing for a good compromise between computational cost and accuracy.
Wave Loads and Ship Motions Evaluated by Linear Strip and Panel Methods
Authors: Karola Aaro , Hirdaris Spyros , Matusiak Jerzy , Mikkola Tommi 
Published: October 2022

Abstract
Despite the rapid development of Computational Fluid Dynamics (CFD) the demand for potential flow hydrodynamics in ship design remains relevant. This is because 2D and 3D Boundary Element Methods (BEM) can be applied for rapid prediction of motions and wave loads. This paper compares results from linear 2D strip-theory and 3D Green function methods with empirical forward speed correction factors in terms of ship motions, radiation forces and wave loads. The former approach applies a “Frank Close-fit” method to solve the radiation problem in 2D. The latter utilizes a pulsating “Green function” source distribution method to solve the radiation problem in 3D. Results are validated against experimental data available for a container ship. It is shown that the motion RAOs obtained by both methods are similar and agree with the experimental values. However, responses in terms of longitudinal distribution of wave loads show discrepancies which increase with wave length shortening and closer to the bow region. An increasing role of diffraction and disregarding forward speed wave making affect the results in short waves. Moreover, it is concluded that solving the linear seakeeping problem is not very sensitive to hull form details and to the modelling of forward speed effects on radiation.
Double Braid Mooring Damper for Floating Offshore Wind Application
Authors: Khalid Faryal , Thies Philipp R. , Halswell Peter , Newsam David , Johanning Lars 
Published: October 2022

Abstract
Introduction of innovative mooring components can reduce the risk and cost associated to mooring systems of floating offshore wind turbines. The Intelligent Mooring System (IMS) is an active, hydraulic, nonlinear mooring component developed by Intelligent Moorings Limited that provides functionality akin to a shock absorber. It offers a combination of desirable stiffness characteristics for floating offshore wind application; an initial compliant response that reduces loads on the structure and a stiffer nonlinear response for larger loads to reduce platform motion and ensure effective station keeping. A salient feature of the IMS is that through variation of the internal pressure, the stiffness of the system can be adjusted in accordance with the prevailing environmental conditions.
This paper presents the results of the physical testing of a double braided IMS at the Dynamic Marine Component test facility and compares the stiffness and strength characteristics to a single braid sleeve. The comparative analysis shows that the stiffness profiles of the double braid for the various configurations are consistent with the single braid design. Importantly, the use of a double braid results in a 50% increase of the tensile strength of the IMS. The investigation presented in this paper will aid in the design of a robust IMS for field testing prior to commercial applications in floating wind installations.
The Effects of Hydrodynamic and Aerodynamic Loads on the Low Frequency Responses of Floating Offshore Wind Turbines
Authors: Land Edward , Brindley Will , Hu Zhiqiang 
Published: October 2022

Abstract
To meet the growing demand for renewable energy and net zero carbon emission targets set by respective governments, offshore wind is looking to move into deeper waters using floating offshore wind turbines (FOWTs) to capture the more consistent winds and expand the area available for energy capture. This has presented the challenge of being able to accurately model FOWTs allowing for the design of cost-effective and reliable structures. In recent years, code comparison studies have revealed that current modelling tools and design techniques used in the industry yield a significant underprediction in low frequency forces and responses with respect to the surge and pitch degrees of freedom. This has been attributed to platforms being excited by nonlinear hydrodynamic forces outside of the linear wave excitation region which are not being properly captured by current market available modelling tools. However, other studies have revealed that aerodynamic loading can produce additional low frequency forces which could in combination give dangerously underpredicted structural loads.
This paper looks to examine the underpredicted forces and responses through use of the in-house developed program ‘DARwind’ and the commercial software OrcaFlex, with an emphasis on the surge degree of freedom motion. The calculations are conducted for a range of different analysis settings and loading conditions in order to compare the contribution of low-frequency loads and the responses of FOWT. In addition, wind load in the simulation will also be divided into two conditions, one is for constant wind speed, and the other is for wind spectrum which considers the low-frequency contribution. It was found that whilst both programs used during this study underpredicted low frequency motion, incorporating various theories and semi-empirical corrections helped reduce this underprediction. This work has allowed for a clearer view of the issues surrounding the underprediction of low frequency loads and responses and will assist in furthering research in this area.
Modified Dam-Break Solution for Green Water on the Deck of an FPSO
Authors: Xia Jinzhu , Liu Huaxing , Sukri Hilmi 
Published: October 2022

Abstract
A modified dam-break solution is proposed to predict green water profiles on the deck of an FPSO through calibration against model test results. The dedicated modifications to the original dam-break solution of Ritter (1892) include: the adoption of the measured speed of waterfront propagation on deck and the calibration of the initial speed of negative surge. These modifications are introduced to address the gaps between the classical dam-break theory assumptions and the actual FPSO green water scenarios. Such gaps include the difference between a body of dead water against a removed dam and an event of freeboard exceedance due to isolated wave run-up, the friction of the deck surface, and the effect of vessel motions in severe sea states. The proposed mathematical formulation is applied based on model test results of a specific spread-moored FPSO design. By comparing the predictions with the measured extreme water height and flow speed on deck for scattered transverse locations, the calibration factors are determined and the water height profile as well as the associated horizontal flow speed along a cross-section is obtained. With the model test measurements of a dedicated wave probe array, the 3D mapping of green water elevation and horizontal speed in all concerned deck areas can be produced. This then forms the basis for green water impact prediction for any object and location of interest on the deck.
Investigations On The Effects Of Internal Liquid Sloshing of Semi-Submersible Floating Offshore Wind Turbines
Authors: Zhou Yang , Qian Ling , Bai Wei , Lin Zaibin 
Published: October 2022

Abstract
Originally developed for civil engineering applications, the tuned liquid column damper (TLCD) has been applied not only on tall buildings but also on floating offshore wind turbines (FOWTs) to minimize structural vibrations. This concept has also been adopted widely in navel architecture to reduce the roll motion. However, whether the damper will bring positive effects on mitigating the dynamic motions of FOWTs remains unknown.
To this end, the paper studies the star-like three columns tuned liquid multi-column damper (TLMCD) impacts on the dynamic motions of a semi-submersible FOWT. The modelling is achieved by using a high-fidelity computational fluid dynamic (CFD) solver based on OpenFOAM. After the verification of the numerical model for the TLMCD system, it is extended to the modelling of the internal sloshing of TLMCD under prescribed pitch motions. A fully coupled floating-sloshing modelling is then conducted to simulate a semi-submersible FOWT with an integrated TLMCD under regular wave conditions. The study indicates that the passive-control TLMCD system has nearly no influence on the translational motions such as surge and heave. However, the pitch motions can be reduced significantly when the incident wave frequency is close to the natural pitch frequency of the platform. Apart from the natural pitch frequency, the TLMCD has a minor effect at other incident wave frequencies.
Treating Agent for Reducing Adsorption Damage of Slick Water on Coal Rock Surface
Authors: Wu Guodong , Li Bojun , Anwaier Maieryemuguli , Li Yuan , Ren Hongda , Yao Erdong 
Published: October 2022

Abstract
Hydraulic fracturing is generally required for coalbed methane to achieve economic production. Slickwater fracturing is one of the most commonly used technology. During fracturing, a million gallons of slickwater are pumped downhole to create fractures, and lots of fluid would filtrate into the formation matrix. The polymers in the fracturing fluid will be absorbed in the porous medium of coal rocks and then decrease the permeability of the reservoir. This paper studies the adsorption amount and the form of slickwater on the coal seam surface and proposes a method to relieve slickwater damage. First, we tested the damage of coal rocks caused by slickwater of different molecular weights. Then the adsorption capacity of different types of slickwater was measured through static adsorption experiments. The changes in adsorption morphology was analyzed according to the micro-morphology of the scanning electron microscope (SEM). Finally, the effect and mechanism of the adsorption release agent were discussed. The study shows that coal seam reservoirs block the gas-liquid percolation channels by forming a water film and polymer adhesion in the pore throat by adsorbing the slick water, resulting in a decrease in permeability and affecting subsequent drainage and gas recovery processes, thereby increasing the damage of slickwater to coal rock. After the improvement of the nano-emulsion NLR, the coal core injury removal rate reached 27.75%, the “gas-liquid-solid” static contact angle of the coal chips was reduced from 129° to 107°, and the surface hydrophilicity was weakened. Adsorption morphology changed from flat and smooth to a rough structure. NMR results prove that NLR reduces adsorption and retention.
Short-Term Analysis of Ship Capsizing Probability in Random Seas
Authors: Chai Wei , He Lin , Leira Bernt J. , Sinsabvarodom Chana , Feng Peiyuan 
Published: October 2022

Abstract
Excessive roll motion in realistic seas is one of the main reasons leading to ship capsizing. However, ship capsizing is a rare event for most of the sea states and prediction of ship capsizing probability is still a challenge. In this work, excessive roll motion for the cases of the dead ship condition and the parametric rolling are studied. Specifically, ship roll response in random seas is calculated by numerical analysis, and a stochastic process, X(t), is defined as the absolute value of the roll motion because the capsizing event can be caused by exceedance of the maximum angle at either side. Two different methods, i.e. the traditional Gumbel method and the average conditional exceedance rate (ACER) method are applied in order to predict the extreme values of the stochastic process X(t). The exceedance probability for X(t) corresponding to the critical levels, such as the flooding angle, can then be employed as an equivalent measure of the ship capsizing probability for a given sea state. The relative merits of the ACER method and the Gumbel method will be compared with Monte Carlo simulation. The studies in this work are intend to promote the understanding of ship capsizing in random seas.
Efficient Long-Term Extreme Response Analysis of Floating Bridges Using Multiple Timescale Spectral Analysis
Authors: Fenerci Aksel , Geuzaine Margaux , Denoël Vincent , Øiseth Ole 
Published: October 2022

Abstract
Floating pontoon bridges offer viable alternatives to cable-supported bridges when crossing long straits. Design of such large floating structures requires estimation of long-term load effects (e.g. 100years) under stochastic wave loading. The long-term extreme response of such floating structures can be estimated using the so-called full-long term method, where the structural response is calculated for all possible environmental conditions over a long-term period. Such a procedure is naturally computationally demanding and depends highly on the computational efficiency of the short-term response calculation. Although the procedure is rather efficient in frequency domain compared to time domain, the computational demand can still be considerable when the number of environmental variables is large. Here, we shall explore the possibility of carrying out the short-term response calculations using multiple timescale spectral analysis, which allows analytical approximations of the short-term response statistics. Through comparisons with the more time-consuming numerical solution, we report reasonably accurate estimations with a significant gain in the computational effort.
New Design Methods for Subsea Power Cables Are Helping the Global Marine Renewable Energy Industry Lower Costs and Improve Reliability
Authors: Griffiths Terry , Draper Scott , Cheng Liang , An Hongwei , Schläppy Marie-Lise , Tong Feifei , Fogliani Antonino , Lipski Wacek , Spradbery Chas , Teng Yunfei , White David , Coles Daniel , Noble Stuart , Doole Siobhan , Johnson Fraser 
Published: October 2022

Abstract
University of Western Australia’s Oceans Graduate School to transform the design methods used to analyse the on-bottom stability of subsea power cables. These cables form the vital connection enabling renewable energy to be reliably and cost-effectively transported from the source to the consumer — whether the collection device at the end of the line is wave, tidal, fixed or floating wind. These novel design methods are equally applicable to umbilicals and other small diameter pipelines. Existing oil and gas pipeline codes overlook much of the physics that is relevant to small diameter pipes and cables. The new research has unlocked significant improvements through new laboratory, numerical and field observational analysis and modelling. The results of this research are presently being incorporated into new design guidance, including the draft British Standards Institute BS 10009 being developed under PEL 114 technical committee guidance.
This paper provides a summary of the research together with observations and lessons learnt in the application of these new design methods to over 7.4 GW of new offshore wind and other renewable energy cables. Given that as at 2020 the global grid-connected total offshore wind capacity was 35 GW, this contribution demonstrates strong evidence of field validation of these research outcomes, as well as their relative importance and transformative potential to contribute to global decarbonisation.
Hydrodynamic Performance of Floating Pontoon Type Breakwater With Skirt Walls and Different Porosity
Authors: Neelamani Subramaniam , AlRagum Alanoud 
Published: October 2022

Abstract
Floating breakwaters (FBW) are widely used in moderate wave climatic conditions. Literature shows that the width of a pontoon type FBW should be about 50% of the incident wavelength in order to achieve 50% wave height reduction at the lee side of the FBW. Hence, for a typical wavelength of 40 m, the width of pontoon FBW needed is about 20 m. Such a FBW may not be cost competitive. Is it possible to reduce the width of the pontoon FBW significantly by adding skirt walls (single, twin, triple or five) under the keel. What will be the effect on mooring forces? In order to get solutions for this problem, experimental investigations were carried out on a typical pontoon type FBW as well as pontoon with skirt walls. Both opaque and porous skirt walls are used. Wave transmission, reflection and mooring forces on both the seaside and lee side are measured. It was found from this study that it is possible to reduce the width of the pontoon by 20 to 40% by introducing three or five skirt walls. However, introducing skirt walls is found to increase the mooring forces by 10 to 30%. A US patent (Patent No. US 9,340,940 B2 dated 17 May 2016) is obtained for the novelty of this study.
Preliminary Experiments for Construction of an Evaluation Model for Methane Hydrate Transportation
Authors: Yamamoto Joji , Nakajima Yasuharu , Yamamoto Marcio , Takano Satoru , Ono Masao , Kanada Shigeo , Otsubo Kazuhisa 
Published: October 2022

Abstract
Methane hydrate has been found below the seafloor in Japan’s Exclusive Economic Zone (EEZ) in a large amount. During the methane hydrate transportation, it is concerned that the riser pipe or the flowline can be plugged by the hydrate reformation and the freezing of seawater. The degradation and reformation kinetics of methane hydrate are mainly controlled by temperature, pressure, and methane concentration in the system, however, it is difficult to predict these factors in the multiphase flow because they are affected by fluid dynamics and heat transfer. Therefore, we are currently constructing an evaluation model for the slurry transportation, including the formation and dissociation processes of the hydrate in a riser pipe at dynamic conditions. Then, the characteristics of the phase change by the hydrate’s formation and dissociation have been investigated using experimental apparatus simulating the flow situations in a riser pipe.
This paper reports some data obtained in two preliminary experiments on the heat transfer effect of pipes and the hydrate formation process. The formation processes of gas hydrate at a gas-liquid interface under high-pressure conditions were observed by using a probe-type video camera. The experimental results showed that the formation of gas hydrate requires enough amount of gas injection, including the dissolved gas in seawater, in addition to temperature-pressure condition.
Lazy Wave Riser Slug Induced Vibration - Modelling Validation
Authors: Minguez Matthieu , Le Prin Kevin , Jara Bravo Cristian , Liné Alain , Cinello Alexandre , Rippol Thierry 
Published: October 2022

Abstract
The paper addresses the mechanical response of a lazy-wave riser system (either rigid or flexible) subject to internal intermittent slug flows. This work makes echo to previous papers (OMAE2020-18620, OMAE2021-60717) proposing novelty and additional features to be either considered in front-end or detailed engineering phases. The focus point of all these studies is the validation of the proposed numerical models to assess the fatigue induced by such complex coupled physics.
This numerical approach suggests coupling both multi-phases flow and mechanical solvers to recover the complex riser response. The coupling is ensured in both time and space to account for the variability of the slug flow properties along the riser. For validation purpose, a large-scale model test (19m long, 2″ diameter) is proposed to (i) characterize the internal slug flow properties along the riser and (ii) monitor the mechanical riser response.
The rough data coming from the large-scale model tests have firstly been exhaustively post-processed to confront the observed internal flow regimes at different locations with some well-known empirical formulations. Then, they are used to discuss the variability of the flow properties along the riser system.
Finally, the proposed coupled modelling is confronted to the experimental data. A very good match is obtained considering the proposed modelling for a large range of flow conditions when comparing the dynamic response of the riser. In the meantime, a simplified method is also introduced and validated for preliminary screening analysis.
The Influence of Added Mass in Ship-Ice-Wave Interactions: A Potential Flow Hydromechanics Model
Authors: Jiang Zongyu , Li Fang , Mikkola Tommi , Kujala Pentti , Hirdaris Spyros 
Published: October 2022

Abstract
For ships navigating in ice floe fields, ship-ice-wave interactions may have significant influence on ship performance and ice impact forces. This is because added mass may affect the hydrodynamic interaction between a ship with ice floes. This paper explores the influence of added mass using a Boundary Element Method (BEM). The model considers the effects of wave frequencies and propagation that are ignored by the conventional Popov (1967) method. Preliminary results are presented for a regular waves scenario whereby a Wigley hull passes by a freely floating ice floe modelled as a round disk. A parametric analysis on the effects of the added mass demonstrates the importance of accounting for multibody interactions.