bluuebunny/crossref_metadata_2025_split huggingface dataset:
Measurement for the Hydrodynamic Coefficients of the Model of an Ultra-Deep Water Work-Class ROV in the O-Tube Facility
Authors: Meng Qingrui , An Hongwei , Kimiaei Mehrdad , Azarhoush Reza 
Published: December 2020

Abstract
Remotely-operated vehicles (ROVs) play an important role in offshore engineering, marine research, submarine rescue, etc., whose hydrodynamic coefficients are significant to their manoeuvrability and stability. The measurements for the hydrodynamic coefficients of an ultra-deep water work-class ROV were conducted using the O-tube facility. The O-tube has a test section with dimensions of 1 m × 1 m × 17.6 m, in which the current velocity up to 3 m/s can be generated. A 1/10 ROV model was held in the centre of the cross-section via a supporting bar with diameter 25 mm. The force signals were acquired from a load cell that could sense three-dimensional forces and moments simultaneously. The measurement strategy was validated via an alternative cuboid model. The three-dimensional forces and moments were obtained subsequently with respect to the bow, stern, top, bottom, and port faces of the ROV model under two steady incoming flow velocities. The results show that the drag coefficient varies within 0.8–1.2 for different faces and the bow face design has significant influence on the drag and pitch moment coefficients when piloting forward.
Extreme Value Estimation of Mooring Loads Based on Station-Keeping Trials in Ice
Authors: Sinsabvarodom Chana , Leira Bernt J. , Chai Wei , Naess Arvid 
Published: December 2020

Abstract
The purpose of this work is to perform an extreme value estimation of the mooring loads associated with station-keeping of a ship operating in ice. In general, the design of mooring lines is based on estimation of the extreme loading caused by environmental conditions within the relevant area. In March 2017, station-keeping trials (SKT) in drifting ice were performed as part of a project headed by Statoil in the Bay of Bothnia. The objective was to investigate the characteristics of the mooring loads for the supply vessel Magne Viking for different types of physical ice management schemes. Tor Viking was employed as an ice breaker as part of the physical ice management systems. The ice conditions (i.e. the ice drift velocity and the ice thickness) during the trials were monitored by using Ice Profiling Sensors (IPSs). Different patterns of ice-breaking manoeuvers were investigated as part of the physical ice management systems, such as square updrift, round circle, circle updrift and linear updrift pattern were studied as part of the field experiments. The peak values of the mooring loads for the supply vessel are determined by using the min peak prominence method. For the purpose of extreme value prediction, the peak over threshold method and block maxima method for a specific time window are applied to estimate the mooring loads that correspond to specific probabilities of exceedance (or equivalently: return periods). These loads can then be compared to the design loads that are being specified by relevant international standards.
Experimental Study of Laminar Displacement Flows in Narrow Horizontal Eccentric Annuli
Authors: Renteria Alondra , Liew Yee Voon , Frigaard Ian 
Published: December 2020

Abstract
Wells with poor cement jobs are prone to develop paths where the hydrocarbons might leak to the surface. Such events cause environmental risks and costly repairs. Even though horizontal wells have been drilled since the 1980s, studies on the dynamics of the fluid-fluid displacement under this configuration are scarce.
In this work, we present experiments on the displacement of two Newtonian fluids in laminar regime in a horizontal uniform annulus. The minimum non-dimensional parameters required to describe the flow under such conditions include a buoyancy number (b), viscosity ratio (μ2/μ1) and eccentricity (e).
We have designed and built a flow loop that mimics the annular displacement under controlled and dimensionlessly comparable conditions found in field. Within this apparatus we can set key process parameters: flow rate, eccentricity, fluid rheology and density. Data acquisition is through imaging with high sensitivity cameras and partially automated instrumentation.
Preliminary results of the experiments show that there is a subtle balance between eccentricity and buoyancy. Sufficiently high values of |b| will end up in stratification of the fluids. The secondary flows created in an eccentric annulus compete against a positive buoyancy, driving the flow to the wide side (top) at moderate values of b. The effect of the viscosity ratio is most relevant at small values of b.
The experimental data from this work can be compared against both mathematical model predictions and computational simulations used in the design of primary cementing jobs.
Research on Resonant Fluid Behaviors and Induced Violent Slamming Effects in a Stepped Moonpool Under Wave Excitations With Ship Forward Speed
Authors: Lyu Hongguan , Gu Jiayang , Tao Yanwu , Zhang Zhongyu 
Published: December 2020

Abstract
Moonpools on drilling vessels are structures located at the mid-ship position to facilitate drilling and other marine operations. The existence of the moonpools is prone to result in intense resonant fluid behaviors even other unexpected violent nonlinear impact on the flow system under external excitations, especially for those types with one or more recesses.
The present study focuses on the resonant fluid behaviors and the induced violent nonlinear effects so-called slamming in a moonpool with a recess within the frameworks of both theoretical and numerical investigations. The natural frequencies of the piston mode and the first-three modes of the studied moonpool are approximated based on the theoretical formulas extracted from the linear potential flow theory. Furthermore, the calculated frequency of piston mode are carried out as the external wave excitations combined with varying current velocity to investigate the slamming effects at the typical locations such as the wall of the moonpool and the bottom of the recess. Finally, the characteristics of the slamming pressure both in space and time are discussed in detail based on the RANS-based numerical simulations.
The result shows that the resonant fluid behaviors under the wave-current interactions are greatly different from the wave-only excitations. Moreover, intense slamming occur in a moon-pool with a recess under some particular wave-current interactions due to the shallow water effects in the recess region and the phenomenon of energy transfer. The phenomenon of slamming must be treated with special cautions in practical engineering because of the fact that some induced adverse effects could weaken the hydrodynamic performance of the drilling vessel, as well as the structural strength of the moonpool.
Analysis of a FOWT Model in Bichromatic Waves: An Investigation on the Effect of Combined Wave-Frequency and Slow Motions on the Calibration of Drag and Inertial Force Coefficients
Authors: do Carmo Lucas H. S. , de Mello Pedro C. , Malta Edgard B. , Franzini Guilherme R. , Simos Alexandre N. , Gonçalves Rodolfo T. , Suzuki Hideyuki 
Published: December 2020

Abstract
The choice of drag and inertia coefficients are critical for the evaluation of hydrodynamic loads in slender cylinders using either Morison’s equation or an approach where viscous forces are simply added to the results of potential theory. Many studies available in the literature have considered fixed cylinders under the action of (two dimensional) sinusoidal currents, showing that the average values of drag and added mass coefficients can be correlated with the Keulegan-Carpenter and Reynolds numbers. However, when the semi-empirical models are used for the analysis of Floating Offshore Wind Turbines (FOWTs), many other aspects of the flow may play an important role, such as the spatial variations of the wave flow over the hull, three-dimensional flow effects associated with the floater motions, the presence of heave plates, among others. The present work is based on a case-study involving a simplified version of the floater of a semi-submersible FOWT and deals with cases where the incoming flow is composed of more than one frequency and body motions are a combination of periodic components with very different frequencies (wave frequency and slow-drift motions). In this case, the choice of proper coefficients for the Morison’s approach becomes somewhat puzzling, to say the least. The objective is to understand how the more complex flow and the coexistence of different frequencies affect the hydrodynamic forces and whether proper values of force coefficients can indeed be obtained from simplified model tests performed in the absence of incoming waves, such as forced oscillations and decay tests. For doing so, the paper analyses the results of an experimental campaign performed with the model scale floater (1:80) composed of four vertical circular columns. Three sets of tests are taken into account: forced oscillations of the hull, free decays of the moored model, and motions under the action of waves (monochromatic and bichromatic). The first two are used to assess the values of added mass and drag coefficients (and also for obtaining linearized damping levels), while the third group of tests helps to evaluate the accuracy of the motions predicted when using these coefficients in frequency-domain computations.
Numerical Simulation of Dynamic Response of Foam Aluminum Sandwich Panel Under Impact Load
Authors: Wan Wenchao , Li Xiaobin , Jiang Li , Li Pu 
Published: December 2020

Abstract
The impact resistance of protective structure directly affects the vitality of the ship. Since the excellent energy absorption characteristics and lightweight structural forms, foamed aluminum sandwich panels have gradually replaced stiffened panels and are widely used in local structures and components of vessels. In order to improve the protective ability of the ship structure, the impact resistance of the foam aluminum sandwich panel is studied in this paper. The deformation mechanism of the foam aluminum sandwich panel under the impact of the foam aluminum projectile is simulated by the finite element analysis, and the effect of different core thickness and core strength on the dynamic response of the sandwich panel is studied. An optimized structural form is proposed for the shear failure of foam aluminum sandwich panels. The results show that the optimized structure improves the impact resistance of foam aluminum sandwich panel and the shear resistance of the intermediate core layer. The research of this paper provides reference for the optimization of foam metal sandwich structure and its application in ship protection structure.
Numerical Investigate of Penetration Resistance of Bucket Foundation With Internal Cylindrical and Cruciform Skirts
Authors: Xiao Zhong , Ma Teng , Liu Haixiao , Zhang Wei , Rafique Muhammad Akbar 
Published: December 2020

Abstract
Bucket foundation has broad application prospects in marine engineering as a competitive foundation. By providing internal cylindrical and cruciform skirts inside the bucket foundation,. the performance of the bucket foundation can be improved . But penetration resistance will also increase. However, few large deformation numerical analysis is carried out to simulate the penetration process of the bucket foundation with internal skirts.
In this paper, three-dimensional large deformation finite element (LDFE) models for bucket foundations with and without internal cylindrical and cruciform skirts considering strain softening effect of soft soil were established using the coupled Eulerian-Lagrangian (CEL) approach. It was found that the elevation of the soil surface inside the bucket is higher than that of initial soil surface when the penetration depth ratio is relatively small for the bucket foundation with internal cylindrical and cruciform skirts. However, with increase of the penetration depth ratio, the increased frictions on the cylindrical and cruciform skirts drive the soil inside the inner cylinder downward, and the elevation of the soil surface inside the inner cylinder is lower than that of initial soil surface. It is also lower than that of soil surface between outer and inner cylinders. The average lateral friction per unit area on each skirt decreases from outer to inner skirt. The soil flow can explain well for the evolution of the penetration resistance.
Projection and Detection Procedures for Long-Term Wave Climate Change Impact on Fatigue Damage of Offshore Floating Structures
Authors: Zou Tao , Kaminski Miroslaw Lech , Li Hang , Tao Longbin 
Published: December 2020

Abstract
The climate change may affect the long-term wave statistics and consequently affect the cumulative fatigue damage. This paper aims to project the trend of annual fatigue damage of offshore floating structures and to detect the climate change impact on the future fatigue damage by coupling a conventional fatigue design method with climate and wave models. Firstly, climate scenarios are selected to project the global radiative forcing level over decadal or century time scales. Secondly, climate models are used to simulate atmosphere circulations and to obtain the wind field data. Thirdly, wave conditions are simulated by coupling wind driven wave models to climate models. Fourthly, stress analysis and fatigue assessments are conducted to project the annual fatigue damage. At last, control simulations are carried out in order to identify the range of natural variability and to detect the human-induced change. A case study is presented in the Sable field offshore South Africa. The results indicate that the significant wave height is considerably influenced by the human-induced climate change. However, this change induced by human activities is still partially masked by the dominant natural variability. In addition, both the significant wave height and the annual fatigue damage increase over century time-scales.
Pipeline Walking due to Temperature Transient: Enhanced Analytical Calculations
Authors: Carneiro Daniel , Carvalhal Renata 
Published: December 2020

Abstract
Pipeline walking induced by transient temperature profiles as the pipeline heats up is assessed. Firstly, an integrated, closed-form solution is given for a problem for which only an ‘incremental’ solution was available [1]. This involves a short pipeline unrestrained at both ends subject to a linearly ramping temperature front.
Secondly, the range of validity of this solution is significantly extended, whilst still presenting it in closed-form. Results are compared with previously published FEA results, presenting remarkable agreement.
The closed-form analytical solution is then compared with FEA of more realistic transients (non-linear temperature front). Results show that the linear simplification can introduce excessive conservatism.
The FEA results are then examined, and the reason for the excessive conservatism is found to be associated to early expansion of the cold end, which is not observed with the simplified linear front. A simplified incremental solution for non-linear transients is proposed. This is shown to be simple and effective in improving prediction for the range over which where the closed form solution is most conservative.
Spectral Fatigue Analysis of Plate Surface Hot-Spots: A Practical Solution to the Stress Direction Issue
Authors: Bigot Fabien , Mougin Stéphanie 
Published: December 2020

Abstract
Spectral Fatigue Analysis using coupled hydrodynamics and finite element models has now become a common practice for the fatigue strength assessment of offshore units, with established procedures given in Classification Rules. However, users are facing a practical issue that is almost never mentioned in the procedures. Indeed, many fatigue hot-spots are located on a plate surface, as opposed to plate edges. For such hot-spots, the finite element model results are the three components of the plane-stress stress tensor. Therefore, the outcome of the Spectral Fatigue Analysis is a set of three transfer functions (RAOs). On the other hand, our industry’s practice regarding the fatigue strength model is still the proven « design S-N curve » approach in combination with the Palmgren-Miner’s damage summation. As a consequence, today the engineer is left with no clear instruction about the proper way how to close this gap between the three stress RAOs on the one hand, and the single stress S-N curve on the other hand. If any advice is given, it is most often to consider the principal stresses, tentatively extending to spectral analysis the classification rule load cases approach. However, principal stress determination is a non-linear procedure that is not compatible with spectral analysis in frequency domain. Turning the spectral results into time domain to overcome this limitation is extremely costly and is not straightforward. Of course, a rational solution to this issue would be the adoption of a multiaxial fatigue damage criteria in lieu of the uniaxial S-N curve. But until such a multiaxial fatigue criteria is widely accepted in our industry, users have to square the circle, and force their stress tensor RAOs into the existing rule criteria. In this paper, a practical solution to reconcile plane stress results and conventional S-N curve criterion in spectral fatigue is proposed: the “facet approach “.
A Fluid-Structure Coupled Computational Model for the Certification of Shock-Resistant Elastomer Coatings
Authors: Ma Wentao , Zhao Xuning , Wang Kevin 
Published: December 2020

Abstract
Shock waves from underwater and air explosions are significant threats to surface and underwater vehicles and structures. Recent studies on the mechanical and thermal properties of various phase-separated elastomers indicate the possibility of applying these materials as a coating to mitigate shock-induced structural failures. To demonstrate this approach and investigate its efficacy, this paper presents a fluid-structure coupled computational model capable of predicting the dynamic response of air-backed bilayer (i.e. elastomer coating – metal substrate) structures submerged in water to hydrostatic and underwater explosion loads. The model couples a three-dimensional multiphase finite volume computational fluid dynamics model with a nonlinear finite element computational solid dynamics model using the FIVER (FInite Volume method with Exact multi-material Riemann solvers) method. The kinematic boundary condition at the fluid-structure interface is enforced using an embedded boundary method that is capable of handling large structural deformation and topological changes. The dynamic interface condition is enforced by formulating and solving local, one-dimensional fluid-solid Riemann problems, which is well-suited for transferring shock and impulsive loads. The capability of this computational model is demonstrated through a numerical investigation of hydrostatic and shock-induced collapse of aluminum tubes with polyurea coating on its inner surface. The thickness of the structure is resolved explicitly by the finite element mesh. The nonlinear material behavior of polyurea is accounted for using a hyper-viscoelastic constitutive model featuring a modified Mooney-Rivlin equation and a stress relaxation function in the form of prony series. Three numerical experiments are conducted to simulate and compare the collapse of the structure in different loading conditions, including a constant pressure, a fluid environment initially in hydrostatic equilibrium, and a two-phase fluid flow created by a near-field underwater explosion.
An Improved SPH Model for Simulating Hydrodynamic Consequences Induced by Reef Degradation
Authors: Zhao Yinlin , Wen Hongjie , Ren Bing , Wang Guoyu , Wang Yongxue 
Published: December 2020

Abstract
Coral reefs degradation accelerates in recent decades due to the natural disturbance and anthropogenic activities. It is important to predict and evaluate reasonably the hydrodynamic consequences of reef degradation. An improved weakly compressible smoothed particle hydrodynamic (WCSPH) porous model is developed based on the standard two-phase mixture theory. The developed WCSPH mixture model is validated by comparing the predicted results with the corresponding available data. The model is then adopted to predict the effects of reef degradation on the spatial distributions of wave setup, wave-induced current and low frequency wave energy over the reef-flat under the reef resonance conditions.
Design of Water Hammer Protection for FPSO Domestic Water System Based on AFT-Impulse
Authors: Huan Zhang , Qipeng Zhang , Chao Wang , Jiangguo Xu , Weiwen Kong 
Published: December 2020

Abstract
Due to the limitation of cabin space, FPSO domestic water pipe network system has the characteristics of long water delivery distance, more bending of pipeline and frequent opening and closing of valves, etc. The above characteristics are very likely to cause water hammer in the pipeline, resulting in increased risk of safe operation of pipe network system. In this paper, a FPSO domestic water system was taken as the research object. In view of the water hammer problem in the pipe network system, the model of FPSO domestic water system was established by using dynamic fluid analysis software AFT-Impulse, combined with the factors affecting the water hammer phenomenon (such as pipe diameter, velocity of wave, pipe length, pipeline roughness and valve closing time), the steady state analysis and transient analysis of multi-working conditions and multi-scenarios were realized to determine the main control factors. Based on the influence of main control factors, a comparison scheme of water hammer protection in FPSO domestic water system was proposed. Through the transient analysis of AFT-Impulse software under multi-working conditions, the optimal scheme of water hammer protection for FPSO domestic water system was obtained, which provided guarantee for the safe operation of the system.
Numerical Design Study of Duct and Stator for a Pump-Jet Propulsor
Authors: Ji Xue-Qin , Yang Chen-Jun , Dong Xiao-Qian 
Published: December 2020

Abstract
The pump-jet propulsor consists of a duct, a rotor and stators which are installed upstream of the rotor to provide pre-swirl flow or downstream of rotor to absorb the kinetic energy in the flow. The strong interactions between the three components and the vehicle are closely related to their design and exert great effect on noise and hydrodynamic performance. This paper attempts to develop an effective and efficient method for the optimal design of the duct and the pre-swirl stators under the influence of vehicle and rotor via viscous flow CFD simulations. In this paper, the two key parameters, attack angle of the duct and pitch angle of pre-swirl stators, are investigated.
The numerical simulations are based on the solution of the Reynolds-Averaged Navier-Stokes (RANS) equations using a two-layer realizable k-ε model for turbulence closure. The computational domain is discretized into mixed unstructured cells. The software package STAR-CCM+ is used for both grid generations and flow simulations.
The rotor is replaced by the body-force model which is proposed according to the load distribution of the rotor in pump-jet propulsor. Total thrust of body force balances the resistance of a fully-appended underwater vehicle and its propulsor in the self-propulsion simulations and torque is determined by assuming that the propulsive efficiency is 80%. To the end of the optimal design, the total resistance, as the main consideration, and detailed flow field, such as pressure distribution, are numerically investigated for varied attack angles of the duct and pitch angles of pre-swirl stator. It is shown that the two parameters have significant impact on the performance of the propulsor and the recommended design is given.