# A Numerical Study on Hydrodynamic Performance of an Inclined OWC Wave Energy Converter with Nonlinear Turbine–Chamber Interaction based on 3D Potential Flow

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## Abstract

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## 1. Introduction

## 2. Materials and Methods

#### 2.1. Numerical Method

#### 2.1.1. Boundary Value Problem

#### 2.1.2. Finite Element Method

#### 2.2. Numerical Validation

#### 2.2.1. Empirical Model for the Duct Orifice

#### 2.2.2. Comparison of Airflow Speed and Pneumatic Pressure

## 3. Results and Discussions

#### 3.1. Hydrodynamic Characteristics of the Inclined OWC chamber

#### 3.2. Three-dimensional Hydrodynamic Effect

#### 3.3. Effect of Shape Parameters

#### 3.3.1. Chamber Length

#### 3.3.2. Skirt Draft

#### 3.3.3. Chamber Inclination

#### 3.3.4. Chamber breadth

## 4. Conclusions

## Author Contributions

## Funding

## Conflicts of Interest

## References

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**Figure 1.**Conceptual view of an inclined oscillating-water-column (OWC) wave energy converter integrated with breakwater.

**Figure 2.**Schematic diagram and boundary conditions for an inclined OWC wave energy converter model.

**Figure 6.**(

**a**) Time-series responses of the inclined OWC chamber; the wave fields around the chamber at each time step (

**b**) ${t}_{a}$ and (

**c**) ${t}_{b}$.

**Figure 7.**Comparison of pneumatic responses between present numerical results and experimental data in regular wave conditions. (

**a**) Airflow speed; (

**b**) pressure drop.

**Figure 9.**Schematic diagram of single-degree-of-freedom (SDOF) system for piston-type motion of OWC with pressure drop.

**Figure 10.**Nonlinearity of pneumatic responses for wave height in regular wave simulation. (

**a**) Airflow speed; (

**b**) pressure drop.

**Figure 12.**(

**a**) Primary energy conversion efficient of OWC chamber for various incident wave conditions; (

**b**) relation between energy conversion efficiency and wave height under condition of peak A and B.

**Figure 13.**Comparison of primary energy conversion efficiency depending on the domain of numerical simulation. (solid line: 3D model; dashed line: 2D model).

**Figure 14.**Wave field around an inclined OWC chamber in 3D simulations under regular wave conditions of (

**a**) peak A, (

**b**) peak B and (

**c**) trough C, (

**d**) trough D in Figure 13 (time step $t={t}_{a}$).

**Figure 15.**Comparison of primary energy conversion efficiency for various sidewall thickness of the OWC chamber.

**Figure 16.**Wave field around an inclined OWC chamber for various sidewall thicknesses under regular wave condition of peak A. (time step $t={t}_{a}$).

**Figure 17.**(

**a**) Primary energy conversion efficiency of OWC chamber for various chamber length (${l}_{c}$); (

**b**) relation between chamber length and incident wavelength under condition of peak B.

**Figure 18.**(

**a**) Primary energy conversion efficiency of OWC chamber for various skirt draft (${d}_{s}$); (

**b**) wave frequency under condition of peak A depending on skirt draft.

**Figure 19.**(

**a**) Primary energy conversion efficiency of OWC chamber for various chamber inclination ($\alpha $); (

**b**) wave frequency under conditions of peak A and B depending on inclination.

**Figure 21.**(

**a**) Primary energy conversion efficiency of OWC chamber for various chamber inclinations ($\alpha $); (

**b**) wave frequency under conditions of peak A and B depending on inclination.

Item | Symbol | Dimension |
---|---|---|

Chamber length | ${l}_{c}$ | 5 m |

Chamber breadth | ${b}_{c}$ | 10 m |

Chamber inclination | $\alpha $ | $1\text{:}1.5(\theta =33.69\xb0)$ |

Skirt draft | ${d}_{s}$ | 2 m |

Water depth | $h$ | 12.8 m |

Dia. of air-duct | ${d}_{d}$ | 0.8 m |

Dia. of orifice | ${d}_{o}$ | 0.32 m |

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## Share and Cite

**MDPI and ACS Style**

Kim, J.-S.; Nam, B.W.; Kim, K.-H.; Park, S.; Shin, S.H.; Hong, K.
A Numerical Study on Hydrodynamic Performance of an Inclined OWC Wave Energy Converter with Nonlinear Turbine–Chamber Interaction based on 3D Potential Flow. *J. Mar. Sci. Eng.* **2020**, *8*, 176.
https://doi.org/10.3390/jmse8030176

**AMA Style**

Kim J-S, Nam BW, Kim K-H, Park S, Shin SH, Hong K.
A Numerical Study on Hydrodynamic Performance of an Inclined OWC Wave Energy Converter with Nonlinear Turbine–Chamber Interaction based on 3D Potential Flow. *Journal of Marine Science and Engineering*. 2020; 8(3):176.
https://doi.org/10.3390/jmse8030176

**Chicago/Turabian Style**

Kim, Jeong-Seok, Bo Woo Nam, Kyong-Hwan Kim, Sewan Park, Seung Ho Shin, and Keyyong Hong.
2020. "A Numerical Study on Hydrodynamic Performance of an Inclined OWC Wave Energy Converter with Nonlinear Turbine–Chamber Interaction based on 3D Potential Flow" *Journal of Marine Science and Engineering* 8, no. 3: 176.
https://doi.org/10.3390/jmse8030176