PREDICTION OF DIFFRACTION FORCES ON A WAVE ENERGY CONVERTER USING BEM AND CFD APPROACH

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Subramanian, A. (2018). PREDICTION OF DIFFRACTION FORCES ON A WAVE ENERGY CONVERTER USING BEM AND CFD APPROACH. Unc Charlotte Electronic Theses And Dissertations.
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Abstract

Alternative energy sources address concerns about fossil fuels such as environmental degradation, public health, and finite energy source. Compared to wind and solar powers, wave power has a higher energy density and is easier to forecast. However, non-linear, complex, and turbulent nature of oceans necessitates a more in-depth flow field analysis before the deployment of wave energy converters (WECs). This research explores the performance of a two-point body absorber WEC, Reference Model 3 (RM3) introduced by the Department of Energy (DOE), to be deployed in North Carolina shores. The wave data from US 192 and US 430 buoy stations were used to calculate the hydrodynamic forces, with focus on the diffraction and Froude-Krylov forces in this work, on the RM3 using1. DOE WEC-Sim, a boundary element method-based (BEM) approach2. Computational fluid dynamics (CFD), a finite volume method-based approachIn the first approach, a full-scale model of RM3 was studied. In the second approach, using the wave characteristics and ocean depth along the North Carolina shores, three scalded RM3 models: 50th, 100th, and 200th, were studied. The developed CFD model based on the volume of fluid (VoF) Eulerian multiphase flow was initially validated with published computational and experimental literature. The realizable k− turbulence model was employed to study the effects of ocean wave turbulence. The validated model was used to study the generated 5th order approximation Stokes wave on the RM3. The grid analysis, using cell sizes ranging from 2.8 million to 9.4 million, verified the appropriate mesh resolution of 7.2 million on the floating part of the RM3. The main challenges faced during the computational domain setup such as free-surfacemeshrefinement, boundary conditions,preventingwavereflection, and scaling the model are elaborated and appropriate solutions are stated. Next step of this research includes modeling the radiation forces to determine the total hydrodynamic forces on the RM3 when deployed as a stand-alone or an array along the North Carolina shores. Also, ongoing experimental testing within the NADGOD research group on scaled RM3 models will be validated and verify the developed CFD model.

Details
Author

Subramanian, Akshith

Title

PREDICTION OF DIFFRACTION FORCES ON A WAVE ENERGY CONVERTER USING BEM AND CFD APPROACH

Physical Description

1 online resource (55 pages) : PDF

Date

2018

Degree Granting Institution

University of North Carolina at Charlotte

Abstract

Alternative energy sources address concerns about fossil fuels such as environmental degradation, public health, and finite energy source. Compared to wind and solar powers, wave power has a higher energy density and is easier to forecast. However, non-linear, complex, and turbulent nature of oceans necessitates a more in-depth flow field analysis before the deployment of wave energy converters (WECs). This research explores the performance of a two-point body absorber WEC, Reference Model 3 (RM3) introduced by the Department of Energy (DOE), to be deployed in North Carolina shores. The wave data from US 192 and US 430 buoy stations were used to calculate the hydrodynamic forces, with focus on the diffraction and Froude-Krylov forces in this work, on the RM3 using1. DOE WEC-Sim, a boundary element method-based (BEM) approach2. Computational fluid dynamics (CFD), a finite volume method-based approachIn the first approach, a full-scale model of RM3 was studied. In the second approach, using the wave characteristics and ocean depth along the North Carolina shores, three scalded RM3 models: 50th, 100th, and 200th, were studied. The developed CFD model based on the volume of fluid (VoF) Eulerian multiphase flow was initially validated with published computational and experimental literature. The realizable k− turbulence model was employed to study the effects of ocean wave turbulence. The validated model was used to study the generated 5th order approximation Stokes wave on the RM3. The grid analysis, using cell sizes ranging from 2.8 million to 9.4 million, verified the appropriate mesh resolution of 7.2 million on the floating part of the RM3. The main challenges faced during the computational domain setup such as free-surfacemeshrefinement, boundary conditions,preventingwavereflection, and scaling the model are elaborated and appropriate solutions are stated. Next step of this research includes modeling the radiation forces to determine the total hydrodynamic forces on the RM3 when deployed as a stand-alone or an array along the North Carolina shores. Also, ongoing experimental testing within the NADGOD research group on scaled RM3 models will be validated and verify the developed CFD model.

Genre

masters theses

Subjects--Topics

Mechanical engineering

Degree

M.S.

Subject Area

Mechanical Engineering

Advisor(s)

Goudarzi, Navid

Committee Members

Keanini, Russell
Uddin, Mesbah

Degree Note

Thesis (M.S.)--University of North Carolina at Charlotte, 2018.

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Rights Holder Information

Copyright is held by the author unless otherwise indicated.

Identifier

Subramanian_uncc_0694N_11970

Permalink

http://hdl.handle.net/20.500.13093/etd:1588