bluuebunny/crossref_metadata_2025_split huggingface dataset:
Shallow Water Equations With Semi-Submerged Structures Solving a Poisson Equation for the Pressure on the Structure Surface
Authors: Schiaveto Neto Luiz André , Rosman Paulo C. C. , Aoun Tannuri Eduardo 
Published: October 2022

Abstract
Interaction between currents and semi-submerged structures in coastal areas is a problem of interest in naval and ocean engineering. CFD commercial codes capable of solving these problems have the drawbacks of the high cost of computational resources and time, making them unsuitable for real-time applications in ship maneuvering simulators.
This work presents a mathematical model that includes semi-submerged structures in the shallow water equations with hydrostatic assumption. The inclusion of a semi-submerged structure implies the addition of a subdomain with no free surface, replaced by the structure surface. The elevation unknown is replaced by the pressure on the structure surface, which is also unknown. Within this subdomain (for the parcel of fluid under the semi-submerged structure), the 2D-integrated continuity equation is replaced by a Poisson-type equation for the pressure on the structure.
This new model is implemented computationally using the finite element method for spatial discretization, and second order schemes for temporal discretization. The results show promising optimization of calculation time per time step, which can lead to the feasibility of real-time applications of hydrodynamic models in ship maneuvering simulators, for example.
The numerical results are compared to simulations performed with a CFD commercial code. It shows fairly good agreement in the current magnitude calculations. The elevation and structure surface results are more discrepant, albeit physically realistic. The analysis of CFD results allows concluding that the inclusion of a 3D module and dynamic pressure estimations may improve the results.
Parametric Modeling Method of Propeller and Reverse Output of 3D Model
Authors: Lu Yu , Wu Chunxiao , Liu Shewen , Gu Zhuhao , Shao Wu , Li Chuang 
Published: October 2022

Abstract
When optimizing the hydrodynamic performance of a propeller, a sufficient sample space for optimization calculations needs to be established and parametric modeling of the initial propeller needs to be implemented. In this paper, the parametric modeling of the propeller is programmed based on the F-spline curve fitting principle, and the radial parameter distributions of the propeller are fitted with one F-spline curve each. The idea of using fewer control variables to fit the curve accurately and minimizing the variance of the fitted points is added to the curve fitting, which greatly reduces the error between the fitted curve and the original curve. Based on the fitted propeller radial parameter curves, the parent propeller shape can be accurately described and the propeller geometry in the generated sample space is guaranteed to be smooth. The fitted curve is then used to write a program that integrates the modeling process and eliminates the need to manually complete the propeller 3D model. The implementation of parametric modeling of the propeller allows for better establishment of the relationship between propeller geometric features and propeller performance. The closed-loop nature of this modeling method ensures efficient propeller hydrodynamic performance forecasting and optimization, and improves the propeller hydrodynamic performance optimization system.
Optimization of a Flexible Flapping-Foil Thruster Based on a Coupled BEM-FEM Model
Authors: Anevlavi Dimitra , Filippas Evangelos , Karperaki Angeliki , Belibassakis Kostas 
Published: October 2022

Abstract
Bio-inspired thrusters designed to mimic the propulsive capabilities and mechanisms of fish locomotion pose an alternative to the conventional autonomous underwater vehicle (AUV) propeller propulsion. In this work, we examine a particular configuration of a flapping-foil thruster, employed for AUV propulsion, operating at a constant speed that undergoes prescribed heaving and pitching oscillations about its pivot axis. An optimization study is performed to determine optimal kinematic parameters and flexural rigidity distribution. The performance assessment of the device is carried out using a fluid-structure interaction (FSI) model based on ideal fluid flow assumptions and Kirchhoff-Love plate theory for cylindrical bending. The proposed coupled boundary element and finite element method (BEM-FEM) has been compared against experimental data and has been found to be suitable for the prediction of the hydroelastic response of such systems. The solver predicts the hydrodynamic forces and the flexural response of the system by treating the non-linear FSI problem. A We comparative analysis between the rigid and the passively deforming flapping-foil thruster designs deduced during the proposed optimization process is performed to illustrate that incorporating bio-inspired features leads to considerable performance enhancement.
Transferability of Meta-Model Configurations for Different Wind Turbine Types
Authors: Müller Franziska , Hübler Clemens , Rolfes Raimund 
Published: October 2022

Abstract
The use of meta-models of aero-elastic simulation models is increasing in wind energy. Here, the question arises whether knowledge about meta-modelling, i.e. meta-model configurations, that has been gained for one wind turbine type can also be transferred to other wind turbine types. Here, knowledge of meta-modelling or meta-model configurations means the choice of meta-model settings, e.g. the underlying functions, the choice of the sampling method as well as the required amount of training data. In this work, the transferability of the Kriging meta-model configurations is analysed for two different offshore wind turbine types, an offshore wind turbine with a monopile foundation and an offshore wind turbine with a jacket foundation. First, the Kriging settings are analysed regarding their transferability. After this, a convergence study is conducted to answer the question whether knowledge regarding the required amount of training data and the selected sampling method are transferable. It turns out that it is possible to use the findings regarding the meta-model settings from the monopile for the jacket as well. The results of both offshore wind turbines are also comparable with regard to the chosen sampling method and the convergence behaviour of the meta-models regarding the required amount of training data. Thus, a transferability of meta-model configurations is generally feasible for the investigated offshore wind turbines and the choice for a specific meta-model is quite robust.
Noise Generation and Propagation From Flapping-Foil Thrusters Used for Marine Propulsion
Authors: Malefaki Iro , Karperaki Angeliki , Belibassakis Kostas 
Published: October 2022

Abstract
In the present work, we focus on noise generation by a flapping foil used for small ship and AUV propulsion and its propagation in the inhomogeneous sea environment. The pressure field and the forces produced by flapping thruster motion, obtained by a BEM model, are used to calculate the dipole and monopole terms associated with the initial-boundary value problem governed by the wave equation. Initially, an acoustic model in free space based on the Farassat formulation is derived. Subsequently, the latter is extended to account for a bounded domain and an inhomogeneous medium. For simplicity, the 2D sea acoustic waveguide is considered, and the presented numerical method is based on a Finite Difference scheme (FDM), incorporating free-surface and seabed effects as well as a variable sound speed profile. Moreover, the numerical scheme is supplemented by a perfectly matched layer (PML) for the treatment of the outgoing radiating field behavior in the open boundaries. Numerical results are presented for the verification of the present method in the case of time-harmonic sources. Future extensions are discussed regarding the application of a Finite Element Method (FEM) – PML scheme to treat localized scatterers and curved boundaries as well as 3D effects.
Experimental Study of Newtonian Laminar Annular Horizontal Displacement Flows With Rotating Inner Cylinder
Authors: Jung Heeseok , Frigaard Ian , Zhang Ruizi , Renteria Alondra 
Published: October 2022

Abstract
During the primary cementing of oil and gas wells, it is increasingly becoming common to slowly rotate the inner casing to aid the mud displacement. We present an experimental study of laminar horizontal displacement of Newtonian fluids with rotating inner cylinder with the experimental setup detailed in (Renteria et al., J. Fluid Mech, 905, 2020). Inner cylinder rotation is able to distort the axial flow to helical. When the rotational viscous force dominates buoyancy force, the displacing fluid follows the helical flow path and displaces the in situ fluid azimuthally around the annulus. The dimensionless rotational speed is defined as the ratio of rotational velocity and axial velocity, which determines the degree of azimuthal dispersion. Even in a buoyancy-dominant displacement, inner cylinder rotation acts to increase the dispersion. Displacement efficiency analysis shows that increasing rotational speed results in improved displacement. For high eccentricity cases, bottom side residual fluids are observed, which can easily be removed by rotating the inner cylinder. In practice, where the entire length of casing is rotated, the effect of rotation is expected to be more significant and improve the displacement.
Experimental and Numerical Studies on the Axial Bearing Behaviour of a Pile Due to Relevant Foundation Fill Material on the Coastal Tidal Flat
Authors: Yao Juntian , Shen Kanmin , Wang Kuanjun , Yu Jian , Huang Maosong 
Published: October 2022

Abstract
The control centers of wind power plants are usually located in coastal tidal flat areas. To ensure the design elevation of the control centres is maintained above the water table, a thick fill will be placed on the original ground level. However, the filling would cause a long-term ground settlement and further lead to the development of the NSF (short for negative skin friction) of the pile foundations for the control centers. In this study, a series of full-scale axial compressive tests were conducted to investigate the effect of fills on the pile bearing behaviour. The numerical analysis method is also established to study the influence of additional ground pressures on the pile axial bearing behavior over time and the influence of NSF caused by consolidation on pile bearing capacity. The rationality is verified by comparisons with the full-scale tests. Finally, a simple procedure is further employed to study the evolution of the long-term pile bearing behavior.
Full-Scale Unsteady RANS Simulations of a 5500DWT Self-Propulsion Tanker
Authors: Ye Bin , Yu Jiawei , Zhang Zhiguo , Long Xin , Feng Dakui 
Published: October 2022

Abstract
Accurately predicting the ship’s speed power performance is a key step in calculating the ship’s energy efficiency design index (EEDI). Recently, numerical simulation using CFD has become a reliable method for predicting the performance of full-scale ships. However, the accuracy of full-scale simulation is still difficult to validate, for the high cost of full-scale sea trials. In this study, the in-house URANS solver based on finite difference method and structured overset grid technology is used for simulation. The PISO algorithm is employed to solve the pressure field, and the six-degree-of-freedom motion (6DOF) equation of rigid body is introduced to predict the ship’s 6DOF motion. The level-set method is adopted to capture the change of free surface. Hydrodynamic performance of a 5500DWT tanker is studied. Firstly, the resistance of the tanker model in calm water is caculated and compared with the towing tank results, and the numerical uncertainty is studied, and then, full-scale self-propulsion performance of the tanker has been simulated. Besides, the sea-trial results of the tanker have been analyzed and corrected to the ideal conditions based on the ITTC sea-trial guidelines and the ISO 15016: 2015 standard. The numerical simulation results were directly compared with the corrected results and showed quite good agreement, which verified the reliability of the CFD solver on the simulation of full-scale ship performance.
Experimental Investigation on Hydrodynamic Forces of Semi-Submerged Cylinder in Combined Steady and Oscillatory Flow
Authors: Hu Tengyan , Ren Haojie , Shen Jiawei , Niu Zhibo , Zhang Mengmeng , Xu Yuwang 
Published: October 2022

Abstract
The hydrodynamic forces on the semi-submerged cylinder under the combination of steady and oscillatory flow are experimentally investigated. The semi-submerged cylinder is forced to move with different periods and amplitudes as towing in the still water to simulate the equivalent combined flow. Compared with the steady flow and oscillatory flow, the feasibility of Morison equation, the hydrodynamic coefficients including drag and added mass coefficients are respectively studied. The results show that the hydrodynamic forces on semi-submerged cylinder in these three types of flows under non-overtopping and overtopping have very different features. The Morison equation is further verified that it can well describe the hydrodynamic force on the semi-submerged cylinder in steady flow and oscillatory flow, while its limitation under combined steady and oscillatory flow when the overtopping occurs is clearly witnessed. The modified Morison equation by changing the of flow velocity squared term to the higher order index term is then proposed. The flow velocity indexes in the modified equation under the non-overtopping and overtopping conditions are respectively determined. The magnification of flow velocity indexes can be clearly found when the overtopping starts to happen. The maximum index can reach 4.4. Moreover, the distributions of drag and added mass coefficients with Froude number and KC number are also observed. This work can provide a useful reference for the design of related marine structures and more valuable guidance for future research.
Numerical Modelling of Liquefaction Around Marine Structures - Progress and Recent Developments
Authors: Windt C. , Goseberg N. , Schimmels S. , Kudella M. , Shanmugasundaram R. , Rusche H. , Sumer B. M. , Kirca V. S. O. , Vanjakula V. , Adam F. , Majewski D. , Kazimierowicz-Frankowska K. , Hrycyna Grzegorz 
Published: October 2022

Abstract
The liquefaction around marine structures can lead to severe structural failure and the susceptibility of seabed soil to liquefaction at a specific installation site of, e.g., floating offshore wind turbines should be included within the design process and site evaluation. To that end, advanced prediction tools based on numerical modelling can provide valuable insight into the hydro-geotechnical processes. However, due to the complex interaction of the underlying physics, developing a holistic modelling framework for seabed liquefaction is a challenging task. The NuLIMAS research project (Numerical modelling of seabed liquefaction around marine structures) aims at the development of such a numerical model of seabed liquefaction implemented in the OpenFOAM® framework. This paper provides an overview of the NuLIMAS project, laying out the current state of the art of experimental and numerical modelling approaches for seabed liquefaction and presenting some initial results.
Effect of Temperature on Resistance to Hydrogen Embrittlement of Dissimilar Metal Welds Subjected to SENB and SENT Testing
Authors: Dodge Michael , Haldorsen Lars Magne , Gittos Mike , Sotoudeh Kasra 
Published: October 2022

Abstract
Dissimilar metal welds (DMWs), as manifested by low alloy steels welded with nickel alloys, are commonly used in subsea production systems. In such applications, there is a risk of hydrogen embrittlement, due to the use of cathodic protection. Historically, one of the most reliable means of establishing the resistance of DMWs to hydrogen embrittlement has been to conduct fracture mechanics-based tests, under representative service conditions. These tests have proved valuable in ranking the performance of various DMWs and, also, emulating the fracture morphologies observed in many subsea failures.
Much of the established data from these tests has been generated using single edge notched bend (SENB) specimens, tested at the seabed temperature, to produce ‘tearing resistance’ J R-curves. However, whilst it is recognized that most failures have occurred after equipment has been shut down, there has been little exploration of how parameters, such as temperature and loading mode, influence the resistance to hydrogen-assisted cracking. This paper uses the results of SENB and single edge notched tension (SENT) tests on DMWs, consisting of 2.25Cr-1Mo Grade F22 welded with ERNiCrMo-3 (Alloy 625), to understand how temperature and level of constraint affect fracture resistance, at a range of temperatures (4 to 80°C). The merits and drawbacks of both techniques are summarized, alongside the practical implications for subsea components currently in operation.
Pipeline Reel-Lay FE Simulation: An Advanced Material Model Calibrated From Testing
Authors: Giry Eric , Shen Chen , Stableford Richard 
Published: October 2022

Abstract
For small to medium size rigid pipelines, reel-laying is an efficient installation method. Higher lay rates are achieved thanks to unreeling rigid pipeline down to seabed. However, the process is mechanically onerous. Pipelines go through successive large bending strains up to 2% or 3%. This is the primary degradation mechanism and affects the mechanical in-service performance of the subsea line. Assessment of material response to the installation sequence is a key point for pipeline engineering. Conventional monotonic material stress-strain relation or cyclic Ramberg-Osgood models are not suitable for repeated large bending sequences or reel-lay installation FE simulations. A parameter-based material model has been tailored for carbon steel seamless pipe under reeling. The evolution of the material behaviour from the first load to stabilised cycle is addressed, by introducing an Abaqus User Subroutine written in FORTRAN. The material properties are programmed in each straining cycle, then active in their corresponding loading cycle. Specimens from DNV450 grades pipe have been tested in an extensive small-scale test and bending trial campaign in order to calibrate finite element model. DIC is used during tensile test and LCF (Low Cycle Fatigue) test to allow accurate measurement on large straining ranges. The parameter-based model can provide response to the first load, including Lüders plateau, up to stabilized hysteresis loop; it is fully parametric by Python. Comparison is made with the more conventional material model or full-scale bending trials demonstrating improved accuracy and agreement with testing. The proposed material model is part of an in-house material model library integrated in a numerical tool package dedicated to rigid pipeline design.
Methodology for Installation of Under-Straight Pipe for Lateral Buckling Mitigation
Authors: Roy Alan , Sriskandarajah Thurairajah , Gunawan Suwarno , Ragupathy Pasupathy , Roberts Graeme , Kassim Yasin , Cederfeldt Markus 
Published: October 2022

Abstract
The residual curvature (RC) method has been implemented by Subsea 7 for lateral buckling mitigation on various projects in recent years. The method involves deploying short sections of under-straight pipe in the catenary from a reel-lay vessel. The objective of this paper is to present RC results on bending moment and curvature and to show how these results can be combined with those from dynamic Orcaflex runs to predict the allowable sea-state for installation.
ABAQUS models to simulate the reeling/unreeling/straightening procedure on one of Subsea 7’s reel-lay vessels are presented, together with a description of the settings adjustment to achieve under-straight pipe with a prescribed level of residual plastic strain. These models describe the pipe profile on the reel, free-span, aligner, passage through the straightener and finally within the catenary to the seabed. The model is used to simulate the deployment of an RC section and to quantify its tendency to rotate in the sag-bend. The dynamic loads are captured by running an equivalent RC section model in Orcaflex.
Results for installation of a typical 14″ × 18″ pipe-in-pipe (PIP) are presented in 115m water depth (WD). Plots showing the spatial distribution of the bending moment and curvature of the RC section at various time increments within the catenary are provided. Attention is focused on the sag-bend. Stress-strain hysteresis loops are presented showing the multiple bending cycles experienced by the RC section from initial spooling-on until eventual deployment on the seabed.
The impact that the RC length, residual plastic strain and ramp angle has on the bending moment/curvature is discussed. Orcaflex results are presented which show dynamic change in curvature at the sag-bend over a typical three-hour interval due to vessel motion. The most characteristic dynamic load (Ref. /15/) on the RC section is calculated to establish the loading envelope seen in the sag-bend region. Checks are also undertaken at other locations to ensure that the dynamic loads are not introducing any additional residual plastic strain in the RC section.
The maximum bending moment seen by the RC section in the sagbend has an important bearing on the allowable sea-state for installation. The presented methodology for calculating the allowable sea-state (combining results of static and dynamic simulations) is a novel feature in the present work.
Roll Stability Evaluation of the Floating Multi-Body System at TML (Twin Marine Lifter) Operation
Authors: Meng Xun , Deng Xingqi , Zhao Shujie , Li Dejiang , Fu Qiang 
Published: October 2022

Abstract
Twin Marine Lifter (TML) is a specially designed heavy-lifting system consisting of two vessels for offshore installation & decommissioning. The system is developed multi-functionally in the heavy lifting sector to be cost-effective. Conceptually, they can be used in tandem for the platform installation and decommissioning of both topsides and jackets or carrying out by single lift configuration for other offshore construction tasks such as wind farm equipment installation. These flexible and versatile solutions to a wider range of potential clients also constrain the shape and the main particulars of the vessels, which results in extra challenges coming from the stability properties of the specific multi-body system compared to traditional single vessel operations, and there are few literatures could be referred to.
In view of the highly complicated motions in the multi-body system at lifting phases, the topological model reflecting the flexible connections among bodies in system during the operation is constructed to obtain theoretical estimation of the roll stability of the targeted decommission topside. The virtual prototype technology based on ADAMS (Automatic Dynamic Analysis of Mechanical Systems) considering the coupling boundary of control factors including capability of the DP power and the compensation system are introduced by experimental data to correctly estimate the influence of multi-body motions on the roll stability of the topside in a synchronized way. A fast analysis and prediction methodology on the roll stability limiting criteria of the multi-body system is proposed. It would provide a safety guarantee and technical support for the design of the specific apparatus and the successful decision making on schemes of a new type of offshore operation mode.