bluuebunny/crossref_metadata_2025_split huggingface dataset:
Plug Cementing Stability
Authors: Vogl Anastasia , Waldal Nile , Sarmadi Parisa , Fershtman Adam , Mitishita Rodrigo S. , Frigaard Ian A. 
Published: October 2022

Abstract
Off bottom plugs are set in both well drilling (kick-off plugs) and in well decommissioning (abandonment plugs). In both cases a dense fluid (cement slurry) is placed over less dense well-bore fluids. In the case of kick-off plugs, viscous pills are commonly used, which can help stabilize this mechanically unstable situation. Abandonment plugs however are often set on top of the freshwater that is used to clean the well prior to abandonment. This is the current practice for many wells in Northwestern Canada. It is a mystery how such cement plugs are able to stay in place for a time sufficient for the cement to thicken and hydrate, but field evidence suggests they do.
In this paper we explore the mechanically unstable scenario of a heavy yield-stress fluid placed on top of a less dense Newtonian fluid in a cylindrical pipe, dimensionally scaled to represent an off-bottom plug. We present details of the experimental setup and its calibration. We then explore the buoyancy-driven exchange flows that occur in transitional parametric regimes between flow and no-flow states, by using both computer modelling and physical experimentation. 3D numerical simulation, using a Volume of fluid method, is carried out to capture the interface between the fluids. The 3D model provides us with a more detailed analysis of the concentration and velocity profiles, along with comparisons to snapshots of the experimental results. The aim is to explore the phenomenology of these unstable flows and be able to estimate timescales of the destabilization. Preliminary results are presented.
The Impact of Extreme Turbidity Flow on Subsea Pipeline Design in a Deepwater Canyon Crossing
Authors: Bai Qiang , Qi Xinhai , Pearl William , Shen Siyuan , Brunner Mark 
Published: October 2022

Abstract
In this paper, finite element (FE) analyses are performed with the commercial software Abaqus to investigate the turbidity-flow-induced behavior of a pipeline crossing the bottom of a deep-water canyon. A general hybrid geotechnical-fluid dynamics approach considering the contributions of fluid drag and soil bearing resistance is used to simulate the hydrodynamic loads imparted to the pipeline due to turbidity currents. By applying an active flow loading over specific lengths while axial and lateral soil resistances are applied to the zones just outside of the turbidity flow region, assessments of the pipeline are performed. Assessments include the following checks: local buckling, lateral deflection, stress/strain in the pipe wall, and the increase in anchor loads at subsea structures in the vicinity.
Although the solution is somewhat limited by modeling idealizations, this sensitivity-based approach, which focuses on a small number of key parameters, provides a useful starting point for pipeline design. Different analytical techniques are suitable for various turbidity flow mitigation options. Both static and dynamic non-linear FE models are utilized to investigate the behavior of the pipeline when subjected to the turbidity flow both with and without mitigation, and an appropriate methodology is established for detailed pipeline design.
Fatigue Analysis of Wind Turbine Blade Coating Considering Uncertainty Due to Voids Subjected to Impact Fatigue
Authors: Kuthe Nikesh , Ahmad Suhail , Mahajan Puneet 
Published: October 2022

Abstract
Wind Turbine Blade (WTB) coating is a protective layer that experiences repetitive raindrop impact. The impacts cause cyclic stresses, fatigue, and erosion of the leading edge of the blade coating which leads to the damage of the WT blade. The presence of voids (manufacturing defects) in the coating leads to local stress concentration and enhances erosion. This erosion can cause an increase in the drag coefficient and reduction in lift coefficient resulting in reduced performance of the WT. In India, the annual monsoon with high-intensity rain makes the problem more critical. FE model was developed using Coupled Eulerian and Lagrangian (CEL) method to calculate stress field due to raindrop impact. In the present case, stress-time histories are random in nature as observed. The stress histories are transformed into respective spectra. The spectrum obtained is converted into simpler cycles using the rain flow cycle counting method. The method is well suited for the fatigue life assessment due to random stresses in the coating of the wind turbine blades under raindrop impact. The cycles thus obtained from the spectrum can be used to estimate the cumulative fatigue life using the Palmgren-Miner rule. This rule assumes that the damage carried out by the sections of a stress signal having a particular range can be estimated and aggregated to the total damage separately from that done by other ranges. Damage evaluation in the coating with the randomly distributed void due to stochastic raindrop impacts is computed from fatigue analysis. The main novelty of this work is fatigue assessment of WTB coating, taking explicit account of uncertainties due to the presence of voids in the erosion phenomenon. Simultaneously reliability analysis is carried out considering the probabilistic distribution of droplet diameter, the velocity of impact, and occurrence of maximum stress due to raindrop impacts in the coating. This model predicts the accurate and reliable life of the coating.
On the Influence of the Soil Stratigraphy on the Monopile Deflection Investigated With FEM in a PISA Framework
Authors: Kanitz Manuela , Mesa Carlos Molina , Berenguer Todo Bom Luís , Dührkop Jan 
Published: October 2022

Abstract
Large diameter monopiles are the most commonly used foundation type for offshore wind farms. The accurate representation of their response to lateral loading to optimise the required pile penetration plays a crucial role in the design of offshore wind farms. Recently, the PISA method proposed by Burd et al.[6] and Byrne et al. [5] has gained importance in the design of monopiles as it more accurately represents the interaction between the monopile and the soil than standard methods. In the PISA project, sand as well as soft and stiff clay were investigated through monotonic pile tests and the PISA parameters to represent the monopile-soil interaction curves were calibrated for each soil type investigated. Normally, the PISA parameters are derived separately for each soil type and then combined in a 1D model to include the soil stratigraphy. However, soil conditions on site are typically heterogeneous and the interaction between different soil layers with different strengths and stiffnesses should be captured. In order to gain a deeper understanding of the influence of soil stratification on pile deflection curves, this paper presents numerical simulations of a large diameter laterally loaded monopile embedded in layered soil using the finite element method (FEM) including a combination of soft clays and dense sands. Based on the FEM results, PISA parameters for the monopile-soil interaction curves are derived and implemented in a 1D beam model to calculate the pile deflection. The results are compared with a 1D model where the PISA parameters are first derived for the individual soil types and then combined to include the same soil stratigraphy. It is shown that the influence of soil stratification on pile deflection is significant. This paper highlights the need for calibration of PISA parameters considering the actual soil stratigraphy present on site.
Empirical Evaluation of Influence of pVARD on Drilling Performance Through Static, Dynamic, and Drilling Applications
Authors: Abugharara Abdelsalam , Jamil Shafaet , Butt Stephen 
Published: October 2022

Abstract
The research of this paper is a continuation on the evaluation of Belleville Springs and Dampening for the passive Vibration Assisted Rotary Drilling (pVARD) tool optimization for drilling operations. The research involves a set of mono versus dual compression tests through involving rotational loading on Belleville Springs and Damping to simulate the rotational drilling performance using pVARD. The reason for involving rotational compression loading during rock drilling is to capture the associated bit-rock interactions and evaluate its relation to the implementation of pVARD versus conventional rotational drilling (no-pVARD). Comprehensive experimental sets on natural isotropic rock drilling using pVARD vs. no-pVARD are conducted under the same conditions of weight on bit (WOB), revolution per minute (rpm), rock type, water flow rate, drill bit. All drilling experiments were conducted at atmospheric pressure using a large-scale and fully instrumented rotary drilling simulator. At first, a full set of static compression tests on Belleville Springs and dampening in combination as well as in individual sets were conducted and displacement versus load relationships were generated. Dynamic motions of pVARD while drilling were also captured and reported. Relationships between pVARD static and dynamic compressions were linked to the drilling performance resulted from pVARD vs. no-pVARD drilling.
Numerical Study of an Alternative Way of Evaluating the Remaining Volume of a Fish Cage
Authors: Tang Hung-Jie , Yeh Po-Hung , Yang Ray-Yeng , Nan Fan-Hua 
Published: October 2022

Abstract
At present, the technology of measuring the net volume of a net cage in the real sea is still rare and limited. This study proposes an alternative way of accessing the remaining volume of an aquaculture net cage in both model and full scales. This new approach is called the alternative reduction coefficient (ARC), which is the ratio of the deformed height between a floating collar and a tube sinker to its original height. Its counterpart is the volume reduction coefficient (VRC), which is the ratio of deformed volume to undeformed volume. In the comparison against the existing experimental studies in the model scale, the maximum error of the current-only case is about 11.6%, and that of the wave-current case is about 23%. For the full-scale fish cage subjected to regular waves and current, the simulated results show that the maximum gap of the remaining volume between ARC and VRC is about 13.6% and 15.3% for current-only and wave-current conditions respectively. The results also show that the greater the wave steepness, the larger the error. Finally, in the simulation of the full-scale net cage subjected to irregular waves and current, the results show that the probabilities of the two methods are both a normal distribution and they are very similar, and the Pearson correlation coefficient of the two methods is about 0.937, the bias of the minimum value is only about 0.73%, that of the maximum value is about 7.18%, and that of the standard deviation is about 5.43%. Therefore, we concluded that ARC is an acceptable method of evaluating the remaining volume of fish cages in the real sea.
Probabilistic Design of Thin-Walled Cylindrical Structures for Application In Large Cargo Submarines
Authors: Jamissen Philip Lundberg , Xing Yihan , Ma Yucong 
Published: October 2022

Abstract
Collapse failure is the dominating failure mode of submarine pressure hulls due to the large hydrostatic pressure, which brings about a low collapse pressure capacity unless thick plates with closely spaced stiffeners are used. However, because cargo submarines require a high payload capacity to be economically attractive, an optimal design with low structural weight is vitally important. This makes thin-walled structures with a high strength-over-weight ratio favourable. Therefore, one crucial challenge relates to the research of large underwater cargo submarine concepts is to propose a cost-effective design for the collapse of the submarine pressure hulls. From experience, the collapse pressure capacity of thin-walled structures is susceptible to the geometric imperfections generated during manufacturing. For a safe design, a common practice used by the design-by-rule approach is introducing a very conservative safety factor. However, such an approach is not structurally efficient. This paper proposes a probabilistic design approach for cylindrical thin-walled structures for application in cargo submarine hulls. The initial imperfections are represented by the Fourier series. Stochastic realisations of the imperfections are made using the Monte Carlo method, and the corresponding collapse pressures are calculated using finite element analysis. The collapse pressures are then collected to plot the cumulative distribution function (CDF). Finally, the collapse pressure capacity can be defined from the CDF based on the desired failure probability. The results show that axial buckling of the thin-walled cylinder is sensitive to the initial imperfection and the distribution of critical buckling force follows Gumbel distribution. In contrast, SST structures subjected to external pressure load are not sensitive to initial imperfections. Gumbel distribution would overpredict the buckling pressure in this case. Also, it is shown that the collapse pressure capacities calculated using probabilistic design are significantly higher than the design-by-rule method.
Experimental Investigation on a Cabin-Suspended Catamaran for Wave Energy Harvesting
Authors: Han Jialin , Li Qiao , Mochizuki Akito , Maeda Teruo , Itakura Hiroshi , Kitazawa Daisuke 
Published: October 2022

Abstract
Wave energy can be a significant factor in the progress towards a carbon-free society. This paper demonstrates the wave energy harvesting performance of a 1/2 scale cabin-suspended catamaran in regular head waves. The catamaran has a twin-seater, the length is 3.28m, and the width is 2.10m. It consists of a suspended cabin, a suspension unit, and a twin-hull. One brushed DC Motor/Generator (M/G) coupled with one gearhead is set at each of the four corners of the cabin’s deck. The shaft of the gearhead connects to a shaft of a pinion gear which meshes with a rack that is fixed on a hull through a ball joint. In this way, the vertical motion of the rack can be transferred into the rotational motion of the pinion causing the M/G generates electrical power. The power generation of the catamaran is experimentally investigated using a Maximum Power Point Tracking (MPPT) technique in a towing tank. Two control algorithms are developed: indirect MPPT and direct MPPT. It is found that the wave energy capture width ratio (CWR) obtained at the direct MPPT is approximately 11% higher than the indirect MPPT when their control parameters are having equal magnitude.
Numerical Investigation of the Effect of Vortex Induced Vibrations (VIV) Parameters on the Behavior of Submarine Power Cables: A Comparison With Scaled Down Experimental Results
Authors: Delizisis Panagiotis , Grivas Konstantinos , De Wilde Jaap , De Ridder Erik-Jan , Resvanis Themistocles L. , Georgallis George 
Published: October 2022

Abstract
For an installed submarine power cable, fatigue is one of the main causes of failure. For static power cables there are cases such as free spans, spans between touch-down point (TDP) and J/I-Tube bell mouth and repair/sea joint procedures that may lead to failure due to fatigue as a result of Vortex-Induced Vibrations (VIV). Similar failure modes are applicable to dynamic cables since they are exposed to current flows for their expected operational life of more than 25 years. Although much research has been done in the field of oil and gas for VIV phenomena on flexible pipe lines, there is no extended and in-depth corresponding literature on submarine power cables. The scope of the present work is to investigate and demonstrate the effect of parameters such as Strouhal number, reduced bandwidth and added mass coefficient on the predicted VIV behavior of submarine power cables, both static and dynamic. The standard industry software SHEAR7 is used in order to assess the effects of each of these parameters. Finally, a comparative study was performed with the results of a scaled down experiment, which took place in the basin of Maritime Research Institute of Netherlands (MARIN) within the scope of the Horizon 2020 (H2020) FLOTANT project and studied the response of a towed dynamic power cable.
Ship Gyroscopic Roll Stabilisation
Authors: Ribeiro e Silva S. , Varela J. M. 
Published: October 2022

Abstract
A thorough understanding of the interaction of waves with ships is a vital factor in the safe and economical technology design. Considerable advances have been made recently in the modelling of wave hydrodynamics and wave-structure interaction. Wave diffraction analysis using 2D Strip Theory (ST) or 3D Boundary Element Methods (BEM) based on potential flow theory is now standard with linear and second-order theory in the frequency domain. In case an assessment of a new ship roll stabilisation system of the gyroscopic type is seen as desirable, no ready to use numerical tool to predict the performance of the wave-structure interaction is available. Therefore, for smaller vessels with a certain advance speed, such a patrol boats or pleasure crafts further developments must be applied to a BEM method to take into account speed corrections plus a standard ST tool in order to include the roll stabilisation effect that could be attained using a dedicated gyroscopic roll stabilisation system installed aboard.
In this framework, the proposed work consists of exploring the application of an adapted BEM method with speed corrections, plus a standard ST to study the wave-structure interactions of an unstabilised ship and a ship fitted with a Gyroscopic Roll Stabilisation (GRS) system by considering the case study of a small patrol boat in a seaway. The main objective of this study is to assess the performance of this GRS concept and calculate the operability index of this class of vessels (percentage of time the vessel complies with user pre-defined limiting criteria) for a certain design point using long term statistics, so that complex non-linear responses in waves will be neglected at this stage.
A Contrastive Study of Two-Time Scaled Method and Unified Method in Maneuverability-in-Waves
Authors: Ma Chengqian , Ma Ning , Gu Xiechong 
Published: October 2022

Abstract
Maneuverability in waves, which is associated with navigation safety and overall operational efficiency, is attracting more and more attention recently. In addition to the experimental method and the pure CFD method, there are two widely used theoretical methods on this topic, the two-time-scale method, and the unified method. However, both methods have theoretical limitations. The two-time-scale method is based on the assumption that the maneuvering frequency varies a lot from the seakeeping frequency. This assumption is not achieved when the ship navigates in following wave conditions or extreme waves. Meanwhile, it is also based on the hypothesis that the total ship motions can be considered as the linear superposition of the maneuvering motion and the seakeeping one. For the unified method, the wave forces rely on the interpolation of the precalculated force coefficients or semi-empirical results in general. Therefore, the comparison between the predicted results using these methods and the experimental results is necessary and valuable to assess the error and advantages of these methods. In the present study, two in-house codes using these methods are developed and utilized to predict the motions of S175 containership in regular waves. The results are obtained and compared with the experimental ones. Finally, the conclusions and assessments on these methods are obtained.
Ultimate Strength Characteristics of Cylindrical Shell in Combined Compression and Bending Moment
Authors: Li Shen , Kim Do Kyun , Benson Simon 
Published: October 2022

Abstract
Many countries have set out their commitments for net-zero emission in order to address the increasingly detrimental impact caused by greenhouse gas and the consequent climate change. To accelerate the ambitious net-zero target while ensuring a sufficient energy supply, the exploitation of wind energy is one of the sustainable and clean solutions. Thus, it is foreseen that the investment in the offshore wind will continue worldwide in the coming years. For a successful deployment of offshore wind turbines, an adequate safety margin of their foundation supporting structures is of paramount importance. Prevailing design codes require a rigorous assessment against the ultimate limit state for the foundation supporting structures of offshore wind turbines. These structures are typically in the form of cylindrical shells, which are subjected to a combination of axial compression and overturning bending moment. In this paper, a numerical study is presented in the light of gaining better insights into the catastrophic collapse behaviour of cylindrical shells under combined loads. Nonlinear finite element analyses considering geometric and material nonlinearities are completed on a parametric range of structural models with different length-to-radius and radius-to-thickness ratios. A matrix of axial compression and bending moment combinations are analysed. The numerical results are compared with prediction by prevailing code formulae.
Sustainable Reuse of Decommissioned Jacket Platforms for Offshore Wind Energy Accounting for Accumulated Fatigue Damage
Authors: Heo Taemin , Liu Ding Peng , Manuel Lance , Correia Jose A. F. O. , Mendes Paulo 
Published: October 2022

Abstract
An offshore energy transition, even if only a gradual one, from carbon-emitting fossil fuel extraction to cleaner sources is recommended, if we are to slow the harmful impacts of climate change. The potential for sustainable reuse of decommissioned offshore jacket platforms to support wind turbines is being considered as an attractive proposition in such a transition. To maximize the benefits of such reuse of assets, what is needed is a rational optimization strategy that considers the remaining life of a repurposed platform, associated retrofit and construction costs, and a future period of gross renewable energy generation following installation of the wind turbine. We outline a study that employs a fatigue reliability-based framework to aid in such sustainable reuse planning and optimization. The framework proposed identifies an optimized reuse plan that incorporates metocean data analysis, structural analysis, life-cycle evaluation, and revenue optimization. We employ a case study and sustainable reuse scenario for a site in the vicinity of Porto, Portugal.
Flow Assurance for Gas-Liquid-Solid Three-Phase Flow at High Void Fraction of Gas Phase for Methane Hydrate Transport
Authors: Takano Satoru , Masanobu Sotaro , Kanada Shigeo , Ono Masao 
Published: October 2022

Abstract
Methane hydrate and subsea minerals have been found in the deepwater within Japan’s exclusive economic zone. However, their development has not reached the commercialization stage because many technical issues still need to be solved.
Gas-lift pumping systems are one of the promising methods for methane hydrate transport from the seafloor to the sea surface. Since the internal flow in pipes becomes a three-phase flow for gas-lift pumping systems, flow assurance for the three-phase flow is essential to design the actual systems.
Gas supplied into pipes deep in the sea expands as it returns to the surface. Thus, the void fractions of the gas phase in lines would be larger near sea surface than near seafloor. In addition, there are few studies on flow assurance in the conditions of a high void fraction of the gas phase.
We conducted the experiment of gas-lift pumping systems using clear polyvinyl chloride pipes and resin balls as solid particles. As a result, we obtained mass flux data, void fractions, and frictional pressure drops in those conditions. Furthermore, we investigated whether the methods previously proposed clould calculate the void fractions and the frictional pressure drops in three-phase flow by comparing the calculated results with experimental data obtained from the present experiment.