Abstract
In this paper, we concerned with the study of an essential and intriguing aspect of fluid with bluff bodies. Mainly, the viscosity is highlighted on the effect of bluff circular and square bodies that immersed in a compressible Newtonian fluid. An accurate Taylor-Galerkin/Pressure-Correction (TG/PC) algorithm is employed to address this phenomenon computationally. In addition, and given the compressible nature of the fluid, determination of density requires to use specific state equation, which is incorporated with the governing fluid equations. The impact of viscosity (u) on various components, encompassing velocity (v), pressure (p), and density (p) represents the main aim in this investigation. Furthermore, a detailed comparison between compressible and incompressible fluids based on the distinct effect arising from bluff bodies of circular or square shapes is provided. The findings emphasized on the reliability and accuracy of the numerical method and aligning consistently with physical phenomena, and its compatibility with the previous research.
Key Words
compressible flow; density; finite element method; Newtonian flow; Taylor-Galerkin/Pressure-Correction method; viscosity
Address
Anas Al-Haboobi: 1Department of Postgraduate Studies, University of Kufa, Kufa, Iraq
Ihssan A. Fadhel: Ministry of Education, General Directorate of Education of Basrah, Basrah, Iraq
Alaa A. Sharhan: Ministry of Education, General Directorate of Education; Baghdad/First Rusafa, Baghdad, Iraq
Alaa H. Al-Muslimawi: Department of Mathematics, College of Sciences, University of Basrah, Basrah, Iraq
Abstract
Mooring system design is critical for the deployment of floating offshore wind farms (FOWF). As the pursuit of offshore wind energy ventures into deeper waters, the application of floating structures is becoming increasingly feasible. Ensuring the stability and efficiency of these structures through robust mooring systems is essential. The paper examines various mooring configurations, evaluates their resilience against a range of environmental conditions, and develops optimized designs tailored for FOWF scenarios. A leap forward for exploiting wind resources in offshore environment setting is represented by FOWFs, which differ from fixed installations by being tethered to the ocean floor, providing the necessary buoyancy and stability for operation in deepwater locales. The key goal of this paper is to design and evaluate mooring systems that maintain both the stability and functional effectiveness of FOWFs, with considerations for environmental loads, coupled dynamic analyses, feasibility, and performance resilience. The paper also investigated existing mooring approaches in the context of FOWFs, analyzed environmental factors affecting mooring performance, used computational simulations to appraise diverse mooring concepts, evaluated the performance of various mooring arrangements, and suggested advancements in mooring solutions suitable for FOWFs. The results showed that the shared mooring systems with taut lines are feasible for 2, 4, 6 and 8 turbines in multiple arrays of FOWF in terms of stability and efficiency. The paper concluded that shared mooring systems are a viable and promising solution for FOWFs in offshore settings at water depths of 200 m.
Key Words
coupled dynamic analysis; floating offshore wind farms; mooring line failure; shared mooring
Address
Wen Jie Tong: Faculty of Mechanical Engineering, Universiti Teknologi Malaysia, Johor Bahru, 81310, Malaysia
Hooi Siang Kang: Faculty of Mechanical Engineering, Universiti Teknologi Malaysia, Johor Bahru, 81310, Malaysia;
Marine Technology Centre, Institute for Sustainable Transport, Universiti Teknologi Malaysia,
Johor Bahru 81310, Malaysia
Gang Ma: Yantai Research Institute, Harbin Engineering University, Yantai, 264006, China
Abstract
In the traditional assessment of ship maneuvering characteristics, the influence of waves on the hydrodynamic behavior of a ship has been disregarded, despite their capacity to alter the kinematics of the surrounding water particles. This alteration, in turn, affects the hydrodynamic forces acting upon the ship, which ultimately leads to modifications in the vessel's steering and control characteristics. In the present study, a scaled model of a container ship was utilized to conduct free running turning circle maneuvers under varying head sea wave conditions, characterized by different wave heights and lengths. Through these tests, we aim to investigate the effects of wave parameters on the vessel's turning characteristics, thereby advancing our understanding of this critical aspect of naval engineering.
Key Words
KCS; ship maneuvering; turning circle; wave
Address
T.V. Rameesha and Kunal N. Tiwari: KSCSTE National Transportation Planning and Research Center, India
Akhil Balagopalan: Admaren Tech Private Limited, India
P. Krishnankutty: Department of Ship Technology, Cochin University of Science and Technology, India
Abstract
Thermal buckling is one of the major problems in offshore pipelines, which affects the structural integrity of the pipeline since it operates under extreme temperatures and high-pressure conditions. The temperature variations across the pipeline's radius govern the critical buckling temperature, arising from heat transfer, especially the natural convection between the working fluid medium and the surrounding fluid medium. In the present study, the finite element tool ANSYS is selected to execute a coupled steady-state thermal and linear eigenvalue buckling analysis on four different types of offshore pipelines: equivalent single-walled pipeline, lined pipeline, sandwich pipeline, and pipe-in-pipe system. The critical buckling temperature of these pipelines is evaluated under subsea and buried conditions, and in comparison, to that of an equivalent single-walled pipeline. The temperature variation and Von Mises stress across the radius of the pipelines are analyzed. The results show that the addition of insulation materials to the pipelines has a significant impact on their critical buckling temperature. The pipe-in-pipe system shows a higher critical buckling temperature than all the other pipelines, exhibiting a significant rise in temperature and outperforming the equivalent single-walled pipeline by 116% and the sandwich pipeline by 34%. Furthermore, the lined pipe's critical bucking temperature is almost the same as that of the equivalent single-walled pipeline.
Address
Balan Raju and Vadivuchezhian Kaliveeran: Department of Water Resources and Ocean Engineering, National Institute of Technology Karnataka India
Abstract
A line-monitoring methodology employing cubic polynomial equations and sensor fusion has been developed to evaluate the global behavior and stress distribution of underwater lines. The approach integrates generalized coordinates with a single global coordinate framework to efficiently and conveniently capture the behavior of geometrically complex lines. The system requires input data including displacements and curvatures at both ends and inclinations along the line, which serve as boundary conditions for the polynomial equations. Using the computed global displacements, other stress-related variables, such as tensile, bending, and nominal stresses, can subsequently be estimated. To validate the proposed methodology, two numerical case studies—a submerged inclined tunnel and a lazy-wave riser—were conducted. Results indicate that the global behavior of the underwater lines is accurately recovered when a sufficient number of sensors are employed although its accuracy can be diminished with less number of sensors. Stress estimation demonstrated higher precision in the submerged inclined tunnel compared to the lazy-wave riser due to the latter's pronounced initial curvature and sharp transitions near the touchdown zones.
Key Words
global behavior; global stress; inclinometers; polynomial equations; riser monitoring; sensor fusion
Address
Chungkuk Jin: Department of Ocean Engineering and Marine Sciences, Florida Institute of Technology,
150 W University Blvd, Melbourne, FL 32901, USA
Ikjae Lee and Moo Hyun Kim: Department of Ocean Engineering, Texas A&M University, Haynes Engineering Building,
727 Ross St, College Station, TX 77843, USA
Seong Hyeon Hong: Department of Mechanical and Civil Engineering, Florida Institute of Technology,
150 W University Blvd, Melbourne, FL 32901, USA
