scholarly journals The Influence of the Chamber Configuration on the Hydrodynamic Efficiency of Oscillating Water Column Devices

2020 ◽  
Vol 8 (10) ◽  
pp. 751
Author(s):  
Ayrton Alfonso Medina Rodríguez ◽  
Jesús María Blanco Ilzarbe ◽  
Rodolfo Silva Casarín ◽  
Urko Izquierdo Ereño
Keyword(s):  
Water Column ◽  
Wall Thickness ◽  
Water Waves ◽  
Numerical Results ◽  
Physical Parameters ◽  
Front Wall ◽  
Linear Wave ◽  
Oscillating Water Column ◽  
Wave Regime ◽  
The Impact

Based on the two-dimensional linear wave theory, the effects of the front wall thickness and the bottom profile of an Oscillating Water Column (OWC) device on its efficiency were analyzed. Using the potential flow approach, the solution of the associated boundary value problem was obtained via the boundary element method (BEM). Numerical results for several physical parameters and configurations were obtained. The effects of the front wall thickness on the efficiency are discussed in detail, then, various configurations of the chamber bottom are presented. A wider efficiency band was obtained with a thinner front wall. In a real scenario having a thinner front wall means that such a structure could have less capacity to withstand the impact of storm waves. Applying the model for the case of the Mutriku Wave Energy Plant (MWEP), findings showed that the proposed bottom profiles alter the efficiency curve slightly; higher periods of the incoming water waves were found. This could increase the efficiency of the device in the long-wave regime. Finally, the numerical results were compared with those available in the literature, and were found to be in good agreement.

scholarly journals Performance of an U-Shaped Oscillating Water Column Wave Energy Converter Device under Oblique Incident Waves

Fluids ◽  
2021 ◽  
Vol 6 (4) ◽  
pp. 137
Author(s):  
Kshma Trivedi ◽  
Santanu Koley ◽  
Kottala Panduranga
Keyword(s):  
Water Column ◽  
Structural Parameters ◽  
Physical Parameters ◽  
Front Wall ◽  
Angle Of Incidence ◽  
Oscillating Water Column ◽  
Energy Converter ◽  
Chamber Length ◽  
Wide Range ◽  
Incident Waves

The present study deals with the performance of an U-shaped oscillating water column device under the action of oblique incident waves. To solve the associated boundary value problem, the dual boundary element method (DBEM) is used. Various physical parameters associated with the U-shaped OWC device, such as the radiation susceptance and conductance coefficients, and the hydrodynamic efficiency, are analyzed for a wide range of wave and structural parameters. The study reveals that the resonance in the efficiency curve occurs for smaller values of wavenumber with an increase in chamber length, submergence depth of the front wall and opening duct, and width of the opening duct. It is observed that with appropriate combinations of the angle of incidence and incident wavenumber, more than 90% efficiency in the U-shaped OWC device can be achieved.

Numerical and Geometrical Analysis of the Onshore Oscillating Water Column Wave Energy with a Ramp

2021 ◽  
Vol 412 ◽  
pp. 11-26
Author(s):  
Marla Rodrigues Oliveira ◽  
Elizaldo Domingues Santos ◽  
Liércio André Isoldi ◽  
Luiz Alberto Oliveira Rocha ◽  
Mateus das Neves Gomes
Keyword(s):  
Water Column ◽  
Wave Energy ◽  
Degrees Of Freedom ◽  
Design Method ◽  
Geometric Analysis ◽  
Relative Difference ◽  
Front Wall ◽  
Multiphase Model ◽  
Oscillating Water Column ◽  
Worst Case

This study is about a two-dimensional numerical analysis of the influence of a ramp in front on an oscillating water column wave energy converter (OWC-WEC). The main purpose was to evaluate, numerically and geometrically, the effect of using a ramp variation in relation to the frontal wall on the hydropneumatic power of the OWC-WEC. The constructal design method was applied for geometric analysis. The problem had a geometric constraint: the area of the ramp (A2) and two degrees of freedom: H2 / L2 (ratio of the height and length of the ramp) and L4 (the distance of the ramp concerning the OWC-WEC front wall). In numerical simulations, the equations of conservation of mass, momentum, and an equation for the transport of volumetric fraction were solved using the finite volume method (FVM). The multiphase model volume of fluid (VOF) was applied for the air-water interaction. Thus, the increase in the H2/L2 ratio resulted in a decrease of the root mean square (RMS) of the available hydropneumatic power (Phyd). By varying the distance L4, the better case was = 6 m and / = 0.025 and the worst case was = 1 m and / = 0.2. The relative difference between the better RMS Phyd = 150.7957 W and the worst Phyd = 73.1164 W reached up to a hundred and six percent.

Uncertainty in Wave Basin Testing of a Fixed Oscillating Water Column Wave Energy Converter

2021 ◽  
Author(s):  
Frances M. Judge ◽  
Eoin Lyden ◽  
Michael O'Shea ◽  
Brian Flannery ◽  
Jimmy Murphy
Keyword(s):  
Water Column ◽  
Wave Energy ◽  
Wave Energy Converter ◽  
Width Ratio ◽  
Oscillating Water Column ◽  
Energy Converter ◽  
The Monte Carlo Method ◽  
Wave Basin ◽  
Measurement Location ◽  
The Impact

Abstract This research presents a methodology for carrying out uncertainty analysis on measurements made during wave basin testing of an oscillating water column wave energy converter. Values are determined for Type A and Type B uncertainty for each parameter of interest, and uncertainty is propagated using the Monte Carlo method to obtain an overall Expanded Uncertainty with a 95% confidence level associated with the Capture Width Ratio of the device. An analysis into the impact of reflections on the experimental results reveals the importance of identifying the incident and combined wave field at each measurement location used to determine device performance, in order to avoid misleading results.

Hydrodynamic Analysis of a Vertical Axisymmetric Oscillating Water Column Device Floating in Finite Depth Waters

2012 ◽  
Author(s):  
Spyros A. Mavrakos ◽  
Dimitrios N. Konispoliatis
Keyword(s):  
Water Column ◽  
Wall Thickness ◽  
Vertical Cylinder ◽  
Finite Depth ◽  
Wave Forces ◽  
Oscillating Water Column ◽  
Wells Turbine ◽  
Present Contribution ◽  
Outer Atmosphere ◽  
Incident Waves

A floating oscillating water column device (OWC) consists of a vertical cylinder, with a finite wall thickness, partly submerged as an open-bottom chamber in which air is trapped above the inner water free surface. The chamber is connected with the outer atmosphere by a duct housing an air turbine. Forced by incident waves from any direction, the water surface inside pushes the dry air above through a Wells turbine system to generate power. In the present contribution the volume flows, the wave forces, the added mass and damping coefficients and the mean second-order loads for various configurations of OWC devices are being presented. Finally, it is tested how differentiations in the device’s geometry (wall thickness, draught, shape of the chamber, turbine characterises) affect the inner pressure and as a result the absorbed power by the device.

Performance of a Shore Fixed Oscillating Water Column Device for Different Bottom Slopes and Front Wall Drafts: A Study Based on Computational Fluid Dynamics and BIEM

2020 ◽  
Vol 143 (3) ◽  
Author(s):  
Piyush Mohapatra ◽  
K. G. Vijay ◽  
Anirban Bhattacharyya ◽  
Trilochan Sahoo
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Water Column ◽  
Wave Energy ◽  
High Efficiency ◽  
Boundary Integral ◽  
Hydrodynamic Performance ◽  
Chamber Pressure ◽  
Front Wall ◽  
Oscillating Water Column

Abstract Oscillating water column (OWC) wave energy converters are one of the most widely researched devices for ocean wave energy harvesting. This study investigates the hydrodynamic performance of a shore-fixed OWC device for different bottom slopes using two numerical approaches, namely, computational fluid dynamics (CFD) and boundary integral equation method (BIEM). In the BIEM method, the boundary value problem is solved in two-dimensional Cartesian coordinates using the linear water wave theory. The CFD model uses a numerical wave tank (NWT) built using the volume of fluid (VOF) method. Numerical computations are carried out for different sloped bottom geometries and front wall drafts to analyze the hydrodynamic efficiency. There is a general agreement between CFD and BIEM results in terms of resonating behavior of the device. It is observed that the front wall draft has a more significant effect, a lower draft leading to a wider frequency band for optimum conversion at high efficiency. While the BIEM-based analysis resulted in improved performance curve for few of the steeper slopes, the CFD study predicted a lower peak efficiency for the same slopes due to the consideration of real fluid characteristics. Detailed performance comparisons are presented using the time histories of free surface elevation, chamber pressure, and streamlines at different time instants within the OWC chamber.

Numerical investigation of front-wall inclination effects on the hydrodynamic performance of a fixed oscillation water column wave energy converter

2018 ◽  
Vol 233 (2) ◽  
pp. 262-271
Author(s):  
M Anbarsooz ◽  
H Rashki ◽  
A Ghasemi
Keyword(s):  
Water Column ◽  
Wave Height ◽  
Wave Energy ◽  
Nonlinear Waves ◽  
Absorption Efficiency ◽  
Hydrodynamic Performance ◽  
Front Wall ◽  
Oscillating Water Column ◽  
Wave Tank ◽  
Highly Nonlinear

One of the main geometrical parameters of the fixed oscillating water column wave energy converters is the inclination angle of front wall. In this study, the effects of this parameter on the hydrodynamic performance of an oscillating water column is investigated using a fully nonlinear two-dimensional numerical wave tank, which is developed using the Ansys Fluent 15.0 commercial software. The accuracy of the developed wave tank is first examined by simulating an oscillating water column, having a front wall normal to the water-free surface, subjected to linear, small amplitude incident waves. The resultant absorption efficiencies are compared with available analytical data in the literature, where a good agreement was observed. Next, the simulations are performed for strongly nonlinear waves, up to the wave steepness of 0.069 ( H/L = 0.069), where H is the wave height and L is the wave length. Results show that the absorption efficiency of the oscillating water column decreases considerably as the wave height increases. Moreover, the maximum wave energy absorption efficiency for the highly nonlinear waves occurs at a pneumatic damping coefficient lower than that of the linear theory. Then, the absorption efficiency of the oscillating water column is determined for eight various front wall configurations at various incident wave periods. Results show that, the front walls that are slightly bent towards the inner region of the oscillating water column chamber are more efficient at some wave periods in comparison with the cases studied in this paper.

scholarly journals Modeling characterization of the vertical and temporal variability of environmental DNA in the mesopelagic ocean

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Elizabeth Andruszkiewicz Allan ◽  
Michelle H. DiBenedetto ◽  
Andone C. Lavery ◽  
Annette F. Govindarajan ◽  
Weifeng G. Zhang
Keyword(s):  
Vertical Distribution ◽  
Water Column ◽  
Temporal Variability ◽  
Mechanistic Model ◽  
Temporal Distribution ◽  
Environmental Dna ◽  
Vertical Displacement ◽  
Physical Parameters ◽  
Spatial And Temporal Variability ◽  
The Impact

AbstractIncreasingly, researchers are using innovative methods to census marine life, including identification of environmental DNA (eDNA) left behind by organisms in the water column. However, little is understood about how eDNA is distributed in the ocean, given that organisms are mobile and that physical and biological processes can transport eDNA after release from a host. Particularly in the vast mesopelagic ocean where many species vertically migrate hundreds of meters diurnally, it is important to link the location at which eDNA was shed by a host organism to the location at which eDNA was collected in a water sample. Here, we present a one-dimensional mechanistic model to simulate the eDNA vertical distribution after its release and to compare the impact of key biological and physical parameters on the eDNA vertical and temporal distribution. The modeled vertical eDNA profiles allow us to quantify spatial and temporal variability in eDNA concentration and to identify the most important parameters to consider when interpreting eDNA signals. We find that the vertical displacement by advection, dispersion, and settling has limited influence on the eDNA distribution, and the depth at which eDNA is found is generally within tens of meters of the depth at which the eDNA was originally shed from the organism. Thus, using information about representative vertical migration patterns, eDNA concentration variability can be used to answer ecological questions about migrating organisms such as what depths species can be found in the daytime and nighttime and what percentage of individuals within a species diurnally migrate. These findings are critical both to advance the understanding of the vertical distribution of eDNA in the water column and to link eDNA detection to organism presence in the mesopelagic ocean as well as other aquatic environments.

HYDRODYNAMIC INVESTIGATION OF A NOVEL CONCEPT OF OWC TYPE WAVE ENERGY CONVERTER DEVICE

2021 ◽  
pp. 1-22
Author(s):  
Kourosh Rezanejad ◽  
Carlos Guedes Soares
Keyword(s):  
Water Column ◽  
Wave Theory ◽  
The Body ◽  
Hydrodynamic Performance ◽  
Bottom Plate ◽  
Linear Wave ◽  
Oscillating Water Column ◽  
Wave Direction ◽  
Linear Wave Theory ◽  
Novel Concept

Abstract The hydrodynamic performance of a novel and efficient concept of a floating Oscillating Water Column device has been investigated. The new concept consists of two chambers. These chambers are positioned on the upstream (fore chamber) and on the downstream (rear chamber) of the incident wave direction. The rear chamber acts mainly similar to a Backward Bent Duct Buoy system, while the design of the fore chamber follows conventional types of Oscillating Water Column systems with the harbour plates (bottom plate as well as side plates) elongated outside of the fore chamber. The primary efficiency of the devised concept has been investigated in the frequency domain. In this context, to solve the corresponding diffraction and radiation problems due to the influence of the air pressure inside the chambers as well as motions of the body, an in-house code has been developed in 2D using the Boundary Element Method based on linear wave theory. The obtained numerical results show that the introduced concept has advanced hydrodynamic efficiency in a broad range of waves.

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