Numerical Examination on the Effect of Internal Fluid Presssure on the Hydrodynamic Response of a Marine Riser

Marine risers are long slender structures which links the floating vessel on the sea surface and its manifold on the sea bottom. It acts as a transportation means for the hydrocarbon resources underneath the sea bed. A riser mainly undergoes hydrodynamic loading which leads to Vortex induced vibrations (VIV) or Flow induced vibrations. These are motions induced on bodies interacting with an external fluid flow producing periodic irregularities on the flow which leads to fatigue damage of offshore oil exploration and production risers. Therefore, suppressing of VIV by providing helical strakes, fairings etc. is necessary in order to reduce the fatigue damage of risers due to hydrodynamic loading. The present paper deals with the numerical study on the response of a marine riserdue to the effect of internalfluid pressure. The initial work is carried out in ANSYS ICEM CFD software. The CFD solution after analysis is obtained from ANSYS FLUENT. The hydrodynamic effects like lift and drag forces along with motion responses is obtained.

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Aerodynamic Analysis on Wind Turbine Aerofoil

International Journal of Engineering & Technology ◽

10.14419/ijet.v7i3.27.17997 ◽

2018 ◽

Vol 7 (3.27) ◽

pp. 456

Author(s):

Albi . ◽

M Dev Anand ◽

G M. Joselin Herbert

Keyword(s):

Wind Turbine ◽

Turbine Blade ◽

Cfd Simulation ◽

Turbine Blades ◽

Wind Turbine Blade ◽

Wind Turbine Blades ◽

Ansys Fluent ◽

Wind Speeds ◽

Drag Forces ◽

Lift And Drag

The aerofoils of wind turbine blades have crucial influence on aerodynamic efficiency of wind turbine. There are numerous amounts of research being performed on aerofoils of wind turbines. Initially, I have done a brief literature survey on wind turbine aerofoil. This project involves the selection of a suitable aerofoil section for the proposed wind turbine blade. A comprehensive study of the aerofoil behaviour is implemented using 2D modelling. NACA 4412 aerofoil profile is considered for analysis of wind turbine blade. Geometry of this aerofoil is created using GAMBIT and CFD analysis is carried out using ANSYS FLUENT. Lift and Drag forces along with the angle of attack are the important parameters in a wind turbine system. These parameters decide the efficiency of the wind turbine. The lift force and drag force acting on aerofoil were determined with various angles of attacks ranging from 0° to 12° and wind speeds. The coefficient of lift and drag values are calculated for 1×105 Reynolds number. The pressure distributions as well as coefficient of lift to coefficient of drag ratio of this aerofoil were visualized. The CFD simulation results show close agreement with those of the experiments, thus suggesting a reliable alternative to experimental method in determining drag and lift.

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Model Test Study on Vortex-Induced Motions of a Floating Cylinder

Volume 5: Polar and Arctic Sciences and Technology; CFD and VIV ◽

10.1115/omae2009-79134 ◽

2009 ◽

Cited By ~ 7

Author(s):

Ying Wang ◽

Jianmin Yang ◽

Tao Peng ◽

Xin Li

Keyword(s):

Circular Cylinder ◽

Scale Model ◽

Visualization System ◽

Forced Motion ◽

Drag Forces ◽

Fluid Field ◽

Helical Strakes ◽

Induced Motion ◽

Motion Characteristics ◽

Lift And Drag

Vortex-Induced Motions (VIM) under current flow is an important issue for surface piercing cylinders, such as Spar platforms and floating buoys, since it affects the motion performance of these structures greatly. In recent years this phenomenon attracts much attention and many researchers have been making efforts to deal with this problem. VIM is such a complicated phenomenon that more fundamental studies are needed to understand the essence behind VIM. This paper mainly concentrates on a circular cylinder, aiming to eliminate outside influences and reveal the inherent characteristic of vortex-induced motion mechanism. A circular cylinder with an aspect ratio of 1:2.4, which could be considered as a scale model for the hard tank of a typical Truss Spar, is studied by experimental method to investigate the surrounding fluid field, the excitation forces and Vortex-Induced Motion characteristics under various governing parameters, such as the current velocity and direction, the mooring stiffness and distribution, the use and efficiency of helical strakes, and so on. By using a simple flow visualization system, the unsteady flow passing the circular cylinder and the vortices in the wake are captured and recorded. The cylinder is tested respectively under fixed, forced-motion and elastically moored conditions. The fluid field, the vortex structures, and the lift and drag forces under fixed and forced-motion conditions are measured, the VIM performance of the cylinder with two different mooring distributions are studied, and strake efficiency is studied considering current directionality and strake height influence.

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Numerical Study of Wind-Tunnel Wall Effects on Lift and Drag Characteristics of NACA 0012 Airfoil

CFD letters ◽

10.37934/cfdl.12.11.7282 ◽

2020 ◽

Vol 12 (11) ◽

pp. 72-82

Author(s):

Mostafa Abobaker ◽

Sogair Addeep ◽

Abdulhafid M. Elfaghi

Keyword(s):

Wind Tunnel ◽

Numerical Study ◽

Published Data ◽

Computational Domain ◽

Tunnel Wall ◽

Ansys Fluent ◽

Slope Correction ◽

Lift Curve ◽

Lift And Drag ◽

Naca 0012

Possible interference effects of the wind tunnel walls play an important role especially for measurements in closed-wall test sections. In this study, a numerical analysis of two-dimensional subsonic flow over a NACA 0012 airfoil at different computational domain heights, angles of attack from 0o to 10o, and operating Reynolds number of 6×106 is presented. The work highlights the role of computational fluid dynamics (CFD) in the investigation of wind tunnel wall effect on lift curve slope correction factor (Ka). The flow solution is obtained using Ansys Fluent software by solving the steady-state continuity and momentum governing equations combined with turbulence model k-v shear stress transport (SST-K?). The numerical results are validated by comparing with the available experimental measurements. Calculations show that the lift curve slope correction results are very close to the published data.

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Design Optimization and Analysis of NACA 0012 Airfoil Using Computational Fluid Dynamics and Genetic Algorithm

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.664.111 ◽

2014 ◽

Vol 664 ◽

pp. 111-116 ◽

Cited By ~ 6

Author(s):

R.K. Ganesh Ram ◽

Yashaan Nari Cooper ◽

Vishank Bhatia ◽

R. Karthikeyan ◽

C. Periasamy

Keyword(s):

Reynolds Numbers ◽

Ansys Fluent ◽

Airfoil Optimization ◽

Drag Forces ◽

Fluent Software ◽

Numerical Computing ◽

Cfd Method ◽

Lift And Drag ◽

Naca 0012 ◽

Mathematical Relations

CFD method is inexpensive method of analysis of flow over aerodynamic structure. It incorporates mathematical relations and algorithms to analyze and solve the problems regarding fluid flow. CFD analysis of an airfoil produces results such as lift and drag forces which determines the ability of an airfoil. Optimization of an airfoil involves improving the design of the airfoil in order to manipulate the lift and drag coefficients according to the requirements. It is a very common method used in all fields of engineering. MATLAB is a numerical computing environment which supports interface with other software. XFoil is airfoil analysis software which calculates the lift and drag characteristics for different Reynolds numbers, Mach numbers and angles of attack. MALAB is interfaced with XFoil and the optimization of NACA 0012 airfoil is done and the results are analyzed. The performance of optimized air foil is analyzed using ANSYS FLUENT software.

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Experimental and Numerical Studies of Vortex Induced Vibration on Cylinder

Jurnal Teknologi ◽

10.11113/jt.v66.2512 ◽

2014 ◽

Vol 66 (2) ◽

Author(s):

M. Mobassher Tofa ◽

Adi Maimun ◽

Yasser M. Ahmed ◽

Saeed Jamei ◽

Hassan Abyn

Keyword(s):

Oil And Gas ◽

Numerical Study ◽

Vortex Induced Vibration ◽

Turbulence Flow ◽

Sea Bed ◽

Severe Fatigue ◽

High Reynolds ◽

Set Up ◽

Viv Suppression ◽

Lift And Drag

Study of vibrations due to vortex shedding (VIV) in the wake of a cylinder that is exposed to current or oscillatory flow is very important, especially for marine risers which are used to extract oil and gas from the sea bed. The phenomenon of vortex induced vibration (VIV) has been one of the major concerns for hydrodynamic researchers due to its potential ability to cause severe fatigue damage. The hydrodynamics of VIV is very complex and still not fully understood. In this paper, some results (amplitude over diameter, lift and drag coefficients) of high Reynolds VIV experiments that are performed in UTM towing tank with an in-house test set-up are presented. A circular cylinder of 114 mm in diameter and 3 min length was towed at constant speed through the basin at Reynolds numbers up to 1.1x105. Model tests with a stationary cylinder and tests with a freely vibrating cylinder were carried out to investigate the influence of VIV on drag coefficient. Later these results are compared with results obtained through 3D numerical simulation, LES is used to solve turbulence flow. It was found that CFD results showed similar trends with experimental results. Results of this paper can be very important to design riser system and future endeavor to perform similar kind of experiments. Successful numerical study of the VIV can also be fruitful for designing efficient VIV suppression devices.

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An Investigation of the Effect of interrupted fin arrangements on the Thermal Performance of a Heat Sink under a Free Convection Condition

Wasit Journal of Engineering Sciences ◽

10.31185/ejuow.vol7.iss1.113 ◽

2019 ◽

Vol 7 (1) ◽

pp. 43-53

Author(s):

Abbas Jassem Jubear ◽

Ali Hameed Abd

Keyword(s):

Heat Transfer ◽

Steady State ◽

Natural Convection ◽

Thermal Performance ◽

Heat Sink ◽

Numerical Study ◽

Ansys Fluent ◽

Fluent Software ◽

Steady State Heat ◽

Steady State Heat Transfer

The heat sink with vertically rectangular interrupted fins was investigated numerically in a natural convection field, with steady-state heat transfer. A numerical study has been conducted using ANSYS Fluent software (R16.1) in order to develop a 3-D numerical model. The dimensions of the fins are (305 mm length, 100 mm width, 17 mm height, and 9.5 mm space between fins. The number of fins used on the surface is eight. In this study, the heat input was used as follows: 20, 40, 60, 80, 100, and 120 watts. This study focused on interrupted rectangular fins with a different arrangement and angle of the fins. Results show that the addition of interruption in fins in various arrangements will improve the thermal performance of the heat sink, and through the results, a better interruption rate as an equation can be obtained.

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Preliminary Results on the Dynamics of a Pile-Moored Fish Cage with Elastic Net in Currents and Waves

Journal of Marine Science and Engineering ◽

10.3390/jmse9010014 ◽

2020 ◽

Vol 9 (1) ◽

pp. 14

Author(s):

Gianluca Zitti ◽

Nico Novelli ◽

Maurizio Brocchini

Keyword(s):

Numerical Model ◽

Laboratory Experiments ◽

Numerical Models ◽

Offshore Structures ◽

Fish Farm ◽

Maximum Displacement ◽

Drag Forces ◽

Real Size ◽

Lift And Drag ◽

Mesh Grid

Over the last decades, the aquaculture sector increased significantly and constantly, moving fish-farm plants further from the coast, and exposing them to increasingly high forces due to currents and waves. The performances of cages in currents and waves have been widely studied in literature, by means of laboratory experiments and numerical models, but virtually all the research is focused on the global performances of the system, i.e., on the maximum displacement, the volume reduction or the mooring tension. In this work we propose a numerical model, derived from the net-truss model of Kristiansen and Faltinsen (2012), to study the dynamics of fish farm cages in current and waves. In this model the net is modeled with straight trusses connecting nodes, where the mass of the net is concentrated at the nodes. The deformation of the net is evaluated solving the equation of motion of the nodes, subjected to gravity, buoyancy, lift, and drag forces. With respect to the original model, the elasticity of the net is included. In this work the real size of the net is used for the computation mesh grid, this allowing the numerical model to reproduce the exact dynamics of the cage. The numerical model is used to simulate a cage with fixed rings, based on the concept of mooring the cage to the foundation of no longer functioning offshore structures. The deformations of the system subjected to currents and waves are studied.

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Numerical study of geometric morphing wings of the 1303 UCAV

The Aeronautical Journal ◽

10.1017/aer.2021.15 ◽

2021 ◽

pp. 1-17

Author(s):

B. Nugroho ◽

J. Brett ◽

B.T. Bleckly ◽

R.C. Chin

Keyword(s):

Flight Control ◽

Numerical Study ◽

Aerodynamic Characteristics ◽

Morphing Wing ◽

Rolling Moment ◽

Wide Range ◽

Morphing Wings ◽

Wing Geometry ◽

Lift And Drag ◽

Wing Morphing

ABSTRACT Unmanned Combat Aerial Vehicles (UCAVs) are believed by many to be the future of aerial strike/reconnaissance capability. This belief led to the design of the UCAV 1303 by Boeing Phantom Works and the US Airforce Lab in the late 1990s. Because UCAV 1303 is expected to take on a wide range of mission roles that are risky for human pilots, it needs to be highly adaptable. Geometric morphing can provide such adaptability and allow the UCAV 1303 to optimise its physical feature mid-flight to increase the lift-to-drag ratio, manoeuvrability, cruise distance, flight control, etc. This capability is extremely beneficial since it will enable the UCAV to reconcile conflicting mission requirements (e.g. loiter and dash within the same mission). In this study, we conduct several modifications to the wing geometry of UCAV 1303 via Computational Fluid Dynamics (CFD) to analyse its aerodynamic characteristics produced by a range of different wing geometric morphs. Here we look into two specific geometric morphing wings: linear twists on one of the wings and linear twists at both wings (wash-in and washout). A baseline CFD of the UCAV 1303 without any wing morphing is validated against published wind tunnel data, before proceeding to simulate morphing wing configurations. The results show that geometric morphing wing influences the UCAV-1303 aerodynamic characteristics significantly, improving the coefficient of lift and drag, pitching moment and rolling moment.

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Numerical Study on the Removal of Hydrogen and Nitrogen from the Melt of Medium Carbon Steel in Vacuum Tank Degasser

Materials Science Forum ◽

10.4028/www.scientific.net/msf.762.253 ◽

2013 ◽

Vol 762 ◽

pp. 253-260 ◽

Cited By ~ 9

Author(s):

Shan Yu ◽

Jyrki Miettinen ◽

Seppo Louhenkilpi

Keyword(s):

Carbon Steel ◽

Liquid Steel ◽

Gas Flow ◽

Numerical Study ◽

Vacuum Treatment ◽

Medium Carbon Steel ◽

Transfer Coefficients ◽

Ansys Fluent ◽

Medium Carbon ◽

Cell Expression

The steelmaking field has been seeing an increased demand of reducing hydrogen and nitrogen in liquid steel before casting. This is often accomplished by vacuum treatment. This paper focuses on developing a numerical model to investigate the removal of hydrogen and nitrogen from the melt of medium carbon steel in a commercial vacuum tank degasser. An activity coefficient model and the eddy-cell expression are implemented in the ANSYS FLUENT code to compute the activities of related elements and mass transfer coefficients of hydrogen and nitrogen in liquid steel. Several cases are simulated to assess the effect of gas flow rate and initial nitrogen content in liquid steel on degassing process and the calculated results are compared with industrial measured data.

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