bluuebunny/crossref_metadata_2025_split huggingface dataset:
Experimental Investigation of Pressure Drop of Gas/Non-Newtonian Flow in Horizontal Pipes
Authors: Ben Rajeb Faraj , Odan Mohamed , Imtiaz Syed , Zhang Yan , Awad Mohamed M. , Rahman Mohammad Azizur 
Published: December 2020

Abstract
Two-phase flow of gas/non-Newtonian fluid through pipes is commonly occurred in chemical industry and oil and gas refinery. Many correlations have been developed to evaluate pressure drop for non-Newtonian fluids. Based on that, these systems are not governed by Newtonian law of viscosity. However, only little experimental work has been devoted to study non-Newtonian flow behavior. In this present work, experimental setup has been conducted to investigate non-Newtonian two-phase (gas/ liquid) flow through pipes. Several concentrations of Xanthan Gum have been used as non-Newtonian liquid in the experiments and compressed air has been used as a gas. The flow rate and pressure of liquid and gas are changed by using a pump placed ahead of the mixing point. Pressure and temperature values are recorded by pressure sensors and thermocouples fixed at specific points along the pipe loop. Results of theses experiments are leaded to come up with experimental model for pressure drop of gas/non-Newtonian flow in pipes. Moreover, the flow regimes of two-phase gas/non-Newtonian flow at different conditions have been visualized through transparent tubes using a high-speed camera.
A Numerical Study of TAD and TLP Platforms Operating Side by Side
Authors: Tong Bo , Chang Rui , Kang Zhuang , Sui Haibo , Li Shaojie 
Published: December 2020

Abstract
A Tender Assisted Drilling (TAD) is typically a support vessel that serves support of a drilling rig, by offering comfortable accommodation for crew and providing additional space where the Drilling Equipment Set is stored and transported. The operation with TAD provides an economical and flexible way for offshore drilling, especially with TLP. Dynamic response of tender-assisted drilling system is crucial due to the safety concern. However, some urgent issue has not been thoroughly studied in tender assisted drilling operation like the hydrodynamic interaction and the impact of nonlinearity cable used. In this paper, a tender assisted drilling system which was taken as the research object was investigated under the metocean conditions of West Africa. The numerical model was established in frequency domain using 3D multi-body diffraction/radiation wave theory and the hydrodynamic interaction is studied in this part. Then two kinds mull-body system with different hawsers arrangements are analyzed by the time domain simulation was performed considering hydrodynamic interaction and the impact of nonlinearity of mooring lines and hawsers. The Time history results of floating body motion and the force on mooring line is compared between two schemes. The results obtained is also investigated by spectral analysis to clearly understand the coupled behavior of such system under these two arrangement.
Estimating Wave Induced Kinematics Underneath Measured Time Histories of Surface Elevation
Authors: Johannessen Thomas B. 
Published: December 2020

Abstract
The present paper is concerned with the accurate prediction of nonlinear wave kinematics underneath measured time histories of surface elevation. It is desired to develop a method which is useful in analysis of offshore measurements close to wind turbine foundations. The method should therefore be robust in relatively shallow water and should be able to account for the presence of the foundation and the shortcrestedness of offshore seastates.
The present method employs measurements of surface elevation time histories at one or a small number of locations and solves the associated velocity potential by minimizing the error in the free surface boundary conditions. The velocity potential satisfies exactly Laplace’s equation, the bed boundary condition and (optionally) the boundary condition on the wall of a uniform surface piercing column. This is achieved by associating one wavenumber with every wave frequency thereby sacrificing the possibility of following the nonlinear wave evolution but ensuring a good description of the wave properties locally. For shortcrested waves, the direction of wave component propagation is drawn from a known or assumed directional spectrum. No attempt is made to calculate the directional distribution of the wave field from the surface elevation measurements since this is usually not realistically possible with the available data.
The method is set up for analysis with or without a uniform current, for shortcrested or longcrested waves and with or without a surface piercing column in the wave field. It has been compared with laboratory data for steep longcrested and shortcrested waves. The method is shown to be in good agreement with measurements. Since the method is based on a Fourier series of surface elevation, however, it cannot model overtopping breaking waves and associated wave impact loading. For problems where wave breaking is important, the method may serve as a screening analysis used to select wave events for detailed analysis using Computational Fluid Dynamics (CFD).
Dimensioning of Rudder Systems for Ice Class Ships
Authors: Hindley Rob , Adams Jillian , Valtonen Ville , Sung Chi-Hyun 
Published: December 2020

Abstract
Rudder systems (rudder control surfaces and steering gear) are a safety critical element of ships operating in ice-covered waters. Icebreaking ships equipped with single rudders are particularly vulnerable considering the remote and often isolated locations in which they operate. The IACS Polar Class Rules were developed as a set of harmonized requirements for ships operating in polar waters. First published in 2006 the rules contain requirements for dimensioning the hull structure and propulsion machinery to resist ice loads. There are however no specific requirements for rudders — the rules simply require appendages to be dimensioned using the hull ice load. This paper presents a series of studies aimed at providing guidance on dimensioning rudders and steering gear systems for operation in ice. Using existing ship reference cases and rudder ice loading scenarios found in previous rules and guidelines a simplified set of design approaches are presented. These approaches are evaluated with Finite Element Analysis and compared with selected measured full-scale data and damage incidents. Guidance is provided on system protection mechanisms for the steering gear under these design and over-load cases. In addition, a comparison is made between the results and those derived from using the hull area design pressures in the current IACS rules.
Collapse Failure Analysis of Subsea Corroded Pipeline Under Combined External Pressure and Axial Force
Authors: Chen Yanfei , He Guoyan , Dong Shaohua , Hou Fuheng , Ma Shang , Hu Dong , Gao Modi 
Published: December 2020

Abstract
The subsea pipelines are usually located in a corrosive external and internal environment. Corrosion presents to be the most common defect type in subsea pipelines, and it is regarded to be one of the main causes of subsea pipeline failure. Due to subsea subsidence, mudslides, and seismic activities, the pipeline is presented under combined external pressure, bending moments and axial force combined loading cases. The accurate determination of the collapse pressure of corroded pipelines under combined loading is important in engineering practice.
On the basis of the finite element method, collapse failure of subsea corroded pipelines under combined loads is investigated. The influence of corrosion length, corrosion width, corrosion depth and diameter-thick ratio on the collapse failure pressure is studied. It is observed that corrosion depth has the most significant impact on pipelines’ collapse capacity. Furthermore, regression equations for predicting the collapse pressure of subsea corroded pipelines are proposed based on numerical results. The solution can be referred to in structural integrity assessment of subsea corroded pipelines.
Fracture Assessment of Flaws in Undermatching Welds
Authors: Vasilikis Daniil , Tkaczyk Tomasz , Pepin Aurelien 
Published: December 2020

Abstract
The criticality of girth weld flaws in subsea pipelines, installed by methods introducing plastic strains such as reel-lay, is usually evaluated through an engineering critical assessment (ECA). Most ECA methodologies require weld overmatch for pipes subjected to plastic deformation. This, however, is not always achievable for corrosion resistant or even carbon steel pipelines. In this case, a material and geometry-specific ECA is often applied.
However, this ECA approach necessitates many 3D finite-element (FE) fracture analyses to be performed. Therefore, the authors propose a simpler screening assessment, which requires undertaking only a limited number of 3D FE fracture analyses. If the significance of a weld undermatch is shown to be negligible then a material and geometry-specific FE-based ECA is deemed unnecessary. Instead, flaw acceptance criteria can be determined under the assumption of weld evenmatch using a material-specific analytical ECA.
The work was undertaken to define and validate the screening assessment process. Subsequently, DNV-GL endorsed the proposed approach which has since been successfully applied on several projects allowing optimization of the project cost and schedule. This paper describes the screening assessment methodology and discusses its application range and limitations. The conclusions and recommendations from a validation program are also provided.
Hydroelastic Analysis of the Bending-Torsional Coupling Vibrations of an Ultra-Large Container Ship
Authors: Li Hui , Lu Lin 
Published: December 2020

Abstract
Springing is a resonance phenomenon between the waves and the ship hull, and the high frequency vibration will threaten the safety of hull structures. With the development of economy, the size of ultra large container ships has been increasing, and the resulting springing and whipping response and their effects has been paid more and more attention. The structure of an ultra large container ship is essentially U-shaped with a low shear center, which results in strong coupling between horizontal bending and torsion. On the other hand, the actual response of hull structures will have an apparently dynamic amplification phenomenon under the effect of springing. In this paper, the wave-induced loads on the hull structure is estimated in the framework of the 3D linear hydroelastic theory, which coupling horizontal and torsional vibration. The vibration characteristics are investigated by using finite element method (FEM), which can get a better calculation accuracy than the simplified calculation method such as the Transfer Matrix Method. And the mode shape of displacement and section loads of the whole ship can be obtained and processed, which is needed for the analysis of hydroelasticity. Finally, in order to consider the effect of the dynamic amplification effect, the dynamic response analysis approach is used for the stress calculation. A 21000TEU is calculated by this method, and the difference between wave-induced and springing-induced section load in frequency domain is shown. Then the results of the frequency response analysis is compared with the quasi-static methods. And the effect of the springing and the dynamic magnification is analyzed.
Experimental Study of Drill Cuttings Transport in Horizontal Well With Newtonian Fluid
Authors: Huque Mohammad Mojammel , Imtiaz Syed , Butt Stephen , Zendehboudi Sohrab , Rahman Mohammad Azizur 
Published: December 2020

Abstract
Transport of cuttings is crucial in a horizontal drilling operation. Effective removal of cuttings is necessary for efficient drilling. An experimental investigation has been carried out to analyze the flow behaviour of solid cuttings in different drilling environments with visualization techniques.
This study investigates the cuttings transport mechanism in a horizontal annulus section. A 6.16 m long and 4.5″ × 2.5″ annulus section was used to model the real-time drilling behaviour with different flow rates, drill pipe rotations and eccentric positions. Water as a Newtonian fluid was used as drilling mud and 2–3 mm solid glass beds were used to simulate the drill cuttings. The in-situ volume fraction of cuttings in the annulus was estimated by Electrical Resistivity Tomography (ERT) analyzer. Visualization technique used to estimate the moving bed velocity in the horizontal annulus section. A highspeed camera was used to capture the transport phenomena of the moving solid particle at 2000 frames per second. The highspeed camera can effectively track each particle in the system. Analysis of high-speed camera revealed different cuttings transport phenomena like rolling of cuttings, stationary cuttings bed and cuttings suspended into the drilling mud.
Experimental investigation revealed that drill pipe rotation helps in cuttings bed movement and resist the formation of large cuttings dune in the annulus formation. Also, this study revealed that eccentric annulus shows less annular solid volume compared to a concentric annulus; however, an eccentric annulus is harder to clean compared to a concentric annulus section.
Flow Induced Vibration Analysis of Topside Piping at High Pressure
Authors: Emmerson Paul R. , Lewis Mike J. , Barton Neil A. , Orre Steinar , Lunde Knud 
Published: December 2020

Abstract
Flow induced vibration (FIV) from high velocity multiphase flow is a common source of vibration concern in process piping, potentially leading to fatigue failures and hydrocarbon leaks. FIV screening methods tend to be conservative for multiphase flows and are typically only validated for simple single bends at low pressure. FE can predict the response of a system if a sensible forcing function is provided. CFD can be used to predict realistic forcing functions in complex combinations of bends and tees, typically seen in process piping systems.
FIV studies were performed on a topside production system operated by Equinor, carrying multiphase flow at high pressure (∼69 bara) conditions, where significant vibration was measured. The study assessed different vibration simulation methodologies, combining FE analysis with forcing functions based on both correlations and CFD simulations. The aim was to gain a better understanding of the accuracy and limitations of calculation methods typically used to assess fatigue.
CFD simulations predicted similar force magnitudes but higher frequency forcing at 69 bara compared to equivalent simulations at atmospheric pressure (at the same liquid and gas superficial velocities). The forcing function correlations used do not predict higher frequency forcing at high pressure, which has a significant impact on the predicted vibration.
Care is required when undertaking this type of analysis. It is important to have an accurate FE model of the as-built pipework and supports as well as a forcing function which accurately represents the fluid forces on the bends. For the case simulated here the magnitude and peak frequency of the forcing function had a significant influence on the response of the structure. Forcing functions based on correlated data from tests at low pressure should be used carefully for high pressure systems. In addition, the inclusion of phasing of the forces at each bend can influence the structural response, and simulations performed in the frequency domain do not consider this.
A combination of CFD and FE modelling offers a potentially powerful tool for assessing and diagnosing multiphase FIV problems in hydrocarbon production piping systems.
Conceptual Design and Model Tests for a Mid-Water Floating Hyperloop Tunnel
Authors: Kemp L. J. , Otto W. J. , Waals O. J. 
Published: December 2020

Abstract
Aviation has a significant impact on the global emission of greenhouse gasses. On the Northern Atlantic route alone there are over 2,500 crossings daily. This illustrates the high demand for connecting people. It is expected that this demand will only increase in the future, which will increase the emissions due to aviation even further. An alternative way for connecting people can be the hyperloop, which obtains comparable speeds while using a fraction of the energy. For intercontinental connections a tunnel would be necessary.
In this study, a conceptual design of a mid-water floating hyperloop tunnel is made and tested on model scale at MARIN. In the present paper the results are discussed of model tests on a mid-water floating tunnel in Atlantic storm conditions at various wave directions and tunnel depths.
The conceptual design of the tunnel is based on (nearly) available technology. One kilometer tunnel segments with a diameter of 11 m are connected to construct a tunnel length of &gt; 5,000 km. Model basin tests are performed on scale 1:110, where a scale model of 140 m length is tested. The tunnel is designed as a neutral buoyant tunnel to reduce complexity and costs for the mooring system. The motions, deformations and mooring line tensions for the tunnel segments are measured by force transducers, accelerometers and an optical measurement system.
Due to flexibility of the slender tunnel segments in combination with a soft mooring system, the tunnel tends to following the incoming waves for certain tunnel depths and wave directions. Only small motions and deformations are allowed for a hyperloop capsule to travel on high speed. The conceptual tests show first results on tunnel depth, structural and geometrical design of an hyperloop tunnel and mooring system.
Basic Research on the Influence of Descent Flow From Small Unmanned Aerial Vehicle (Quadcopter) on a Small Floating Body
Authors: Ji Mingyao , Srinivasamurthy Sharath , Nihei Yasunori 
Published: December 2020

Abstract
Currently, unmanned aerial vehicles (UAV), are playing an active role in various situations. However, because of its size and other limitations, the commonly used UAVs (from now on, just called as drone) do not have the long endurance capabilities of large aircraft. Of course, long flight is not the original intention of its design, but flexibility is its main characteristic. This results in the need for frequent replacement and recharging of battery equipment. It may be easy to replace the batteries on land, but it will be more difficult to do the same offshore. Also, there is always the danger of drone falling into the water due to insufficient power. To overcome this problem, it is imagined to place a floating body such that the drone can be docked as and when necessary while flying over the water for maintenance and battery replacement.
Therefore, in this preliminary study, we aim to model the basic physical phenomena mainly on how the drone’s descent flow affects structures such as small floating bodies. The effects of drone descent flow on a small floating body and resulting load distribution was investigated both experimentally and numerically. Further, the mechanism of drone descent flow was examined in detail.
The drift simulation of the floating body due to the drone descent flow was performed with high accuracy, and the model of the drone’s descent flow became clear.
Design of Dynamic High Voltage Cables for Floating Substation
Authors: Guignier Lucie , Mariani Riccardo , Cottet-Emard Arthur , Toumit Stéphane , Choisnet Thomas 
Published: December 2020

Abstract
This paper presents the design and performance assessment of 220kV dynamic export cables for a floating substation characterized by a ring-shaped floater known as Damping Pool.
The main originality of the design presented is that the cables considered have dry conductors. They are shielded from the water by a longitudinally welded corrugated copper sheath. Similar cables have been operating at lower voltage levels and thus with thinner insulation thicknesses.
The export cable configuration has been designed considering environmental conditions representative of both the Central North Sea, Pacific Coast of Japan or the US, in 100m water depth. Ultimate and fatigue limit-state design verification of the configuration are made through nonlinear time-domain analysis using coupled models comprising the floating substation hull, the mooring system and dynamic export cables. Fatigue limit-state design verification is based on the fatigue properties of the cable section, combined with appropriate S-N curves of the armour layers and metallic screen-sheath.
Design verifications show that the dynamic export cable configuration proposed could satisfactorily meet the performance requirements for a service life over 25 years, considering proven cable equipment such as a bend stiffener remaining within today’s manufacturer molding capacities.
Numerical Wave Tank Simulation of a Variable Geometry Wave Energy Converter
Authors: Zou Shangyan , Abdelkhalik Ossama 
Published: December 2020

Abstract
This paper presents a high-fidelity numerical wave tank simulation for Variable Geometry Wave Energy Converters (VG-WECs). Typically, wave energy converters require reactive power to optimize the energy conversion, which significantly jeopardizes the economic index of the system. The proposed VGWECs allows comprehensive shape-changing not only in response to ocean climate but also to reduce the reactive power requirements on the power take-off (PTO) unit. This design aims at eliminating reactive power with minimal impact on optimality in terms of energy production. To investigate the dynamic behavior of the VGWEC, this model is simulated in a Computational Fluid Dynamics (CFD) based Numerical Wave Tank (CNWT) using ANSYS 2-way Fluid Structure Interaction (FSI) tool. The interaction between irregular waves and the VGWEC is simulated. The numerical results show that the proposed VGWEC has large deformation and motion in response to the incoming wave. This highly nonlinear interaction between waves and VGWEC can be leveraged to eliminate reactive power.