scholarly journals Comparison of wave load effects on a TLP wind turbine by using computational fluid dynamics and potential flow theory approaches

2015 ◽  
Vol 53 ◽  
pp. 142-154 ◽  
Author(s):  
Ali Nematbakhsh ◽  
Erin E. Bachynski ◽  
Zhen Gao ◽  
Torgeir Moan
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Wind Turbine ◽  
Potential Flow ◽  
Flow Theory ◽  
Wave Load ◽  
Potential Flow Theory ◽  
Load Effects

scholarly journals Comparison of Hydrodynamic Load Predictions Between Reduced Order Engineering Models and Computational Fluid Dynamics for the OC4-DeepCwind Semi-Submersible

2014 ◽  
Author(s):  
Maija A. Benitz ◽  
David P. Schmidt ◽  
Matthew A. Lackner ◽  
Gordon M. Stewart ◽  
Jason Jonkman ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Potential Flow ◽  
International Energy Agency ◽  
Computational Cost ◽  
Flow Theory ◽  
Computer Aided Engineering ◽  
Potential Flow Theory ◽  
Floating Offshore Wind Turbines ◽  
Computer Aided

Hydrodynamic loads on the platforms of floating offshore wind turbines are often predicted with computer-aided engineering tools that employ Morison’s equation and/or potential-flow theory. This work compares results from one such tool, FAST, the National Renewable Energy Laboratory’s wind turbine computer-aided engineering tool, and the high-fidelity computational fluid dynamics (CFD) package, OpenFOAM, for the OC4-DeepCwind semi-submersible analyzed in the International Energy Agency Wind Task 30 project. Load predictions from HydroDyn, the offshore hydrodynamics module of FAST, are compared with results from OpenFOAM. HydroDyn uses a combination of Morison’s equation and potential-flow theory to predict the hydrodynamic forces on the structure, at a small computational cost compared to CFD. The implications of the assumptions in HydroDyn are evaluated based on this code-to-code comparison.

Benchmarking of a Computational Fluid Dynamics-Based Numerical Wave Tank for Studying Wave Load Effects on Fixed and Floating Offshore Structures

2017 ◽  
Vol 139 (3) ◽  
Author(s):  
Ali Nematbakhsh ◽  
Zhen Gao ◽  
Torgeir Moan
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Offshore Structures ◽  
Numerical Results ◽  
Wave Loads ◽  
Numerical Wave Tank ◽  
Wave Load ◽  
Wave Tank ◽  
Load Effects ◽  
Numerical Wave

A computational fluid dynamics (CFD) based numerical wave tank (NWT) is developed and verified to study wave load effects on fixed and free floating offshore structures. The model is based on solving Navier–Stokes equations on a structured grid, level set method for tracking the free surface, and an immersed boundary method for studying wave–structure interaction. This paper deals with establishing and verifying a CFD-based NWT. Various concerns that arise during this establishment are discussed, namely effects of wave reflection which might affect the structure response, damping of waves in downstream, and three-dimensional (3D) effects of the waves. A method is described and verified to predict the time when incoming waves from wave generator are affected by reflecting waves from the structure which can help in better designing the dimensions of NWT. The model is then used to study sway, heave, and roll responses of a floating barge which is nonuniform in density and limited in sway direction by a spring and damper. Also, it is used to study wave loads on a fixed, large diameter, surface piercing circular cylinder. The numerical results are compared with the experimental and other numerical results, and in general very good agreement is observed in all range of studied wave frequencies. It is shown that for the studied fixed cylinder, the Morison equation leads to promising results for wavelength to diameter ratio larger than 2π (kD < 1), while for shorter wavelengths results in considerable over prediction of wave loads, due to simplification of wave diffraction effects.

scholarly journals A weak-scatterer potential flow theory-based model for the hydroelastic analysis of offshore wind turbine substructures

2021 ◽  
Vol 238 ◽  
pp. 109702
Author(s):  
V. Leroy ◽  
E.E. Bachynski-Polić ◽  
A. Babarit ◽  
P. Ferrant ◽  
J.-C. Gilloteaux
Keyword(s):  
Wind Turbine ◽  
Potential Flow ◽  
Flow Theory ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Potential Flow Theory ◽  
Hydroelastic Analysis

Application of Potential Flow Theory to Plane-Strain Extrusion

1967 ◽  
Vol 89 (3) ◽  
pp. 503-511 ◽  
Author(s):  
A. Shabaik ◽  
S. Kobayashi ◽  
E. G. Thomsen
Keyword(s):  
Plane Strain ◽  
Potential Flow ◽  
Flow Line ◽  
Flow Theory ◽  
Flow Fields ◽  
Potential Flow Theory ◽  
Good Agreement

Theoretical and experimental flow fields of several extrusion ratios of lead in plane strain were compared. It was found that, for extrusion ratios where dead metal exists, the agreement between the potential and experimental flow nets was better for small reductions when a modified boundary approaching a flow line was used. It was also found that when the flow changed direction gradually, the potential flow net was in good agreement with the experimental one. The solution obtained is unique and complete.

scholarly journals Design and Analysis of a Wind Turbine Blade with Dimples to Enhance the Efficiency through CFD with ANSYS R16.0

2018 ◽  
Vol 207 ◽  
pp. 02004
Author(s):  
M. Rajaram Narayanan ◽  
S. Nallusamy ◽  
M. Ragesh Sathiyan
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Wind Turbine ◽  
Wind Turbines ◽  
Turbine Blades ◽  
Electrical Energy ◽  
Optimum Combination ◽  
Surface Topology ◽  
Wind Turbine Blades ◽  
Lift And Drag

In the global scenario, wind turbines and their aerodynamics are always subjected to constant research for increasing their efficiency which converts the abundant wind energy into usable electrical energy. In this research, an attempt is made to increase the efficiency through the changes in surface topology of wind turbines through computational fluid dynamics. Dimples on the other hand are very efficient in reducing air drag as is it evident from the reduction of drag and increase in lift in golf balls. The predominant factors influencing the efficiency of the wind turbines are lift and drag which are to be maximized and minimized respectively. In this research, surface of turbine blades are integrated with dimples of various sizes and arrangements and are analyzed using computational fluid dynamics to obtain an optimum combination. The analysis result shows that there is an increase in power with about 15% increase in efficiency. Hence, integration of dimples on the surface of wind turbine blades has helped in increasing the overall efficiency of the wind turbine.

Passing Ship Effects in Non-Uniform Water Depth

2016 ◽  
Author(s):  
Lilan Zhou ◽  
Ji Yang ◽  
Qian Wang ◽  
Jiangtao Qin
Keyword(s):  
Time Domain ◽  
Potential Flow ◽  
Flow Model ◽  
Flow Theory ◽  
Propagation Model ◽  
Beach Erosion ◽  
Wave Flow ◽  
Generation Model ◽  
Theory Method ◽  
Potential Flow Theory

Waves generated by passing ships have potential adverse impacts on the environment (beach erosion, ecological disturbance, structures damage) and other waterway users (navigations, moored ships) in the coastal and sheltered areas. But issues related to waves of ships were addressed rarely in China until now. Accurate prediction of wash waves is the first step to control the washes from passing ships and it’s significant to reduce the effects of washes. A coupled method is used in this paper to simulate the washes and its effects caused by the passing ship. A potential flow theory method is adopted as the stationary wave generation model; a non-hydrostatic wave flow model is used as the wave propagation model; a time domain method is chosen as the model for simulating the forces and moments of mooring ship. The waves calculated by a potential flow theory method in the near field are used as the input for the non-hydrostatic wave-flow model to obtain the far field waves. A time-domain representation of the wave-cut at the location of the passing vessel is transformed to the frequency-domain and is used as the input for the diffraction computations. Parts of the calculated results are validated experimentally, satisfactory agreement is demonstrated.

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