Numerical Study of the Effect of the Relative Depth on the Overtopping Wave Energy Converters According to Constructal Design

2014 ◽  
Vol 348 ◽  
pp. 232-244 ◽  
Author(s):  
Elizaldo Domingues dos Santos ◽  
Bianca Neves Machado ◽  
Marcos Moisés Zanella ◽  
Mateus das Neves Gomes ◽  
Jeferson Avila Souza ◽  
...  
Keyword(s):  
Wave Energy ◽  
Numerical Study ◽  
Strong Dependence ◽  
Geometric Optimization ◽  
Relative Depth ◽  
Multiphase Model ◽  
Constructal Design ◽  
Wave Energy Converters ◽  
Low Head ◽  
Volume Method

The conversion of wave energy in electrical one has been increasingly studied. One example of wave energy converter (WEC) is the overtopping device. Its main operational principle consists of a ramp which guides the incoming waves into a reservoir raised slightly above the sea level. The accumulated water in the reservoir flows through a low head turbine generating electricity. In this sense, it is performed a numerical study concerned with the geometric optimization of an overtopping WEC for various relative depths:d/λ = 0.3, 0.5 and 0.62, by means of Constructal Design. The main purpose is to evaluate the effect of the relative depth on the design of the ramp geometry (ratio between the ramp height and its length:H1/L1) as well as, investigate the shape which leads to the highest amount of water that insides the reservoir. In the present simulations, the conservation equations of mass, momentum and one equation for the transport of volumetric fraction are solved with the finite volume method (FVM). To tackle with water-air mixture, the multiphase model Volume of Fluid (VOF) is used. Results showed that the optimal shape, (H1/L1)o, has a strong dependence of the relative depth, i.e., there is no universal shape that leads to the best performance of an overtopping device for several wave conditions.

Analysis of Geometric Variation of Three Degrees of Freedom through the Constructal Design Method for a Oscillating Water Column Device with Double Hidropneumatic Chamber

2019 ◽  
Vol 396 ◽  
pp. 22-31
Author(s):  
Yuri T.B. Lima ◽  
Mateus das Neves Gomes ◽  
Camila F. Cardozo ◽  
Liércio André Isoldi ◽  
Elizaldo D. Santos ◽  
...  
Keyword(s):  
Water Column ◽  
Degrees Of Freedom ◽  
Numerical Study ◽  
Design Method ◽  
Geometric Optimization ◽  
Oscillating Water Column ◽  
Constructal Design ◽  
Wave Energy Converters ◽  
Volume Method ◽  
Geometric Variation

This paper presents a biphasic two-dimensional numerical study of sea wave energy converters with operating principle being Oscillating Water Column (CAO) devices with two couples chambers. For the study of the geometric optimization, the Constructal Design method is applied in association with the exhaustive search method to determine the geometric arrangement that leads to the greatest hydropneumatic power available. The objective function is the maximization of hydropneumatic power converted by the device. The constraints of the problem are the inflow volumes of the hydropneumatic chamber (VE1, VE2), the total volumes (VT1, VT2) and the thicknesses of the device columns (e1, e3). The degrees of freedom analyzed were H1/L1(ratio between height and length of the hydropneumatic chamber of the first device), H2/L2 (ratio between height and length of the hydropneumatic chamber of the second device), H2 (height of the column dividing the two devices) and e2 (thickness of the column dividing the devices). In the present work the degree of freedom H6 (depth of immersion of the device) is kept constant and equal to H6 = 9.86 m. The Finite Volume Method (FVM) was used in the numerical solution of the equations employed. For the treatment of the interaction between the air and water phases, the Volume of Fluid (VOF) method was applied. The results show that the maximum hydropneumatic power available was 5715.2 W obtained for degrees of freedom H1/L1 = H2/L2 = 0.2613 and e2 = 2.22 m. The case of lower performance has a power value equal to 4818.5 W with degrees of freedom equal to H1/L1 = H2/L2 = 0.2613 and e2 = 0.1 m.

Numerical and Experimental Analysis of a Hybrid Wind-Wave Offshore Floating Platform’s Hull

2018 ◽  
Author(s):  
Thiago S. Hallak ◽  
José F. Gaspar ◽  
Mojtaba Kamarlouei ◽  
Miguel Calvário ◽  
Mário J. G. C. Mendes ◽  
...  
Keyword(s):  
Wave Energy ◽  
Experimental Analysis ◽  
Wind Wave ◽  
Numerical Study ◽  
Energy Devices ◽  
Wave Energy Converters ◽  
Wave Basin ◽  
Hybrid Concept ◽  
Point Absorbers ◽  
The Stability

This paper presents a study regarding a novel hybrid concept for both wind and wave energy offshore. The concept resembles a semi-submersible wind platform with a larger number of columns. Wave Energy Devices such as point absorbers are to be displayed around the unit, capturing wave energy while heaving and also enhancing the stability of the platform. In this paper, a first numerical study of the platform’s hull, without Wave Energy Converters, is carried out. Experiments in wave basin regarding the same unit have been conducted and the results are presented and compared to the numerical ones. Both stability and seakeeping performances are assessed and compared.

Constructal Design of Wave Energy Converters

2012 ◽  
pp. 275-294 ◽  
Author(s):  
E. D. dos Santos ◽  
B. N. Machado ◽  
N. Lopes ◽  
J. A. Souza ◽  
P. R. F. Teixeira ◽  
...  
Keyword(s):  
Wave Energy ◽  
Constructal Design ◽  
Wave Energy Converters ◽  
Energy Converters

scholarly journals Control-Informed Geometric Optimization of Wave Energy Converters: The Impact of Device Motion and Force Constraints

Energies ◽  
2015 ◽  
Vol 8 (12) ◽  
pp. 13672-13687 ◽  
Author(s):  
Paula Garcia-Rosa ◽  
Giorgio Bacelli ◽  
John Ringwood
Keyword(s):  
Wave Energy ◽  
Geometric Optimization ◽  
Wave Energy Converters ◽  
The Impact ◽  
Energy Converters

scholarly journals GEOMETRIC EVALUATION USING CONSTRUCTAL DESIGN OF A COASTAL OVERTOPPING DEVICE WITH DOUBLE RAMP CONSIDERING A REGULAR WAVE AND TIDAL VARIATION

2019 ◽  
Vol 18 (1) ◽  
pp. 64
Author(s):  
J. C. Martins ◽  
M. M. Goulart ◽  
L. A. Isoldi ◽  
E. D. dos Santos ◽  
M. N. Gomes ◽  
...  
Keyword(s):  
Electricity Generation ◽  
Numerical Study ◽  
Renewable Energy Sources ◽  
Tidal Effect ◽  
Tidal Variation ◽  
Constructal Design ◽  
Wave Energy Converters ◽  
Search Field ◽  
The Waves

Concern for the environment and new ways of electricity generation, have led to studies of renewable energy sources, among these the Wave Energy Converters (WECs) are an option, however there are still many challenges to define how best to realize the conversion of the energy of the waves into electricity. In this work, a numerical study was carried out with the purpose of maximizing the available power (Pd) of a two-ramp overtopping device, considering the area fraction of ramps (ϕ1 and ϕ2) equal to 0.0006 and the ratio between height and length of the ramps (H1/L1 = H2/L2) equal to 0.3. The distance between the ramps (Lg) was varied in three values: 1.0; 1.5 and 2.0 m, besides three values for the free surface of water (h): 9.8; 10.0 and 10.2 m; simulating a tidal effect. The Constructal Design and Exhaustive Search methods were used, respectively, in the geometric evaluation (determination of a search field) and optimization. For the wave generation, the Second Order Stokes Theory was used, with wave period (T) of 7.5 s and wave height (H) 1.0 m. The results showed that there was no accumulation of water in the upper ramp of the device, in addition, with the increase of Lg there was an increase of Pd in h = 10.0 and 10.2 m, and Pd kept practically constant in h = 9, 8 m. And, as expected, with increasing of h, there was an increase in Pd.

scholarly journals GEOMETRIC EVALUATION OF FOUR STAGGERED CYLINDERS ARRAY SUBJECTED TO FORCED CONVECTIVE FLOWS BY MEANS OF CONSTRUCTAL DESIGN

2019 ◽  
Vol 18 (1) ◽  
pp. 57
Author(s):  
A. P. D. Aghenese ◽  
F. B. Teixeira ◽  
L. A. O. Rocha ◽  
L. A. Isoldi ◽  
J. F. Prolo Filho ◽  
...  
Keyword(s):  
Degrees Of Freedom ◽  
Numerical Study ◽  
Design Method ◽  
Fluid Dynamic ◽  
Working Fluid ◽  
Convective Flows ◽  
Constructal Design ◽  
Staggered Arrangement ◽  
Forced Convective Flow ◽  
Volume Method

This work presents a numerical study on the geometric evaluation of forced convective flows over four staggered arrangement of four cylinders. The forced convective flow is considered incompressible, two-dimensional, laminar and unsteady. Geometry varies according to Constructal Design method. The objectives are the maximization of Nusselt number (NuD) and minimization of drag coefficient (CD) between the cylinders and the surrounding flow. Simulations were performed considering Reynolds numbers of ReD = 10, 40 and 150 and air as working fluid, i.e., Prandtl number is assumed Pr = 0.71. The problem presents three degrees of freedom: ST/D (ratio between transversal pitch of the intermediate cylinders and the cylinders diameter), SL1/D (ratio between the frontal and intermediate cylinders longitudinal pitch and the cylinders diameter) and SL2/D (ratio between the intermediate and posterior cylinders longitudinal pitch and the cylinders diameter). However, SL1/D and SL2/D measures were kept fixed at 1.5 and ST/D varies in the range 1.5 ≤ ST/D ≤ 5.0. The conservation equations of mass, momentum and energy conservation are solved with the Finite Volume Method (FVM). Optimal results for fluid-dynamic study in all ReD cases occurred for the lowest values of ST/D, i.e., (ST/D)o,f = 1.5. For thermal analysis, NuD behavior was assessed, where optimal results for ReD = 10 and 40 occurred for the highest values of ST/D, whilst, for ReD = 150, the optimal value was achieved for the intermediate ratio of ST/D = 4.0.

scholarly journals NUMERICAL STUDY COMPARING THE INCIDENCE INFLUENCE BETWEEN REALISTIC WAVE AND REGULAR WAVE OVER AN OVERTOPPING DEVICE

2019 ◽  
Vol 18 (1) ◽  
pp. 46
Author(s):  
R. G. Hübner ◽  
P. H. Oleinik ◽  
W. C. Marques ◽  
M. N. Gomes ◽  
E. D. dos Santos ◽  
...  
Keyword(s):  
Numerical Study ◽  
Fluid Dynamic ◽  
Multiphase Model ◽  
Regular Wave ◽  
Sea State ◽  
Fluent Software ◽  
The Difference ◽  
Discrete Values ◽  
Table Data ◽  
Volume Method

This work presents a numerical study to evaluate the difference between the fluid dynamic behavior of an overtopping device subjected to the incidence of a realistic wave when compared to a regular one; being this regular wave representative of the considered realistic sea state. To do so, the FLUENT software was employed, which is a Computational Fluid Dynamics package based on the Finite Volume Method. The regular wave was generated through a User Defined Function (UDF) that imposes its velocities components as boundary conditions of prescribed velocity. On the other hand, for the realistic wave it was used a methodology to impose the realistic components velocities from transient discrete values, named Table Data (TD) in FLUENT software. For both cases the Volume of Fluid (VOF) multiphase model was applied in the treatment of the water-air interaction. The results showed that the amount of water accumulated in the reservoir for the realistic sea state was 2.46 higher than for the regular wave. This is a relevant finding, since several researches about Overtopping device efficiency were promoted considering only the incidence of regular wave.

scholarly journals CONSTRUCTAL DESIGN OF A VORTEX TUBE FOR SEVERAL INLET STAGNATION PRESSURES

2012 ◽  
Vol 11 (1-2) ◽  
pp. 85 ◽  
Author(s):  
C. H. Marques ◽  
L. A. Isoldi ◽  
E. D. Dos Santos ◽  
L. A. O. Rocha
Keyword(s):  
Turbulent Flows ◽  
Degrees Of Freedom ◽  
Vortex Tube ◽  
Numerical Study ◽  
Cylindrical Tube ◽  
Navier Stokes ◽  
Working Fluid ◽  
Computational Domain ◽  
Constructal Design ◽  
Volume Method

The present paper shows a numerical study concerned with the geometrical optimization of a vortex tube device by means of Constructal Design for several inlet stagnation pressures. In the present study, it is evaluated a vortex tube with two-dimensional axisymmetric computational domain with dry air as the working fluid. The compressible and turbulent flows are numerically solved with the commercial CFD package FLUENT, which is based on the Finite Volume Method. The turbulence is tackled with the k-ε model into the Reynolds Averaged Navier-Stokes (RANS) approach. The geometry has one global restriction, the total volume of the cylindrical tube, and four degrees of freedom: d3/D (the ratio between the diameter of the cold outlet and the diameter of the vortex tube), d1/D (the ratio between the diameter of the inlet nozzle and the diameter of the vortex tube), L2/L (the ratio between the length of the hot exit annulus and the length of the vortextube) and D/L (the ratio between the diameter of the vortex tube and its length). The degree of freedom L2/L will be represented here by the cold mass fraction (yc). In the present work it is optimized the degrees of freedom yc and d3/D while the other degrees of freedom and the global restriction are kept fixed. The purpose here is to maximize the amount of energy extracted from the cold region (cooling effect) for several geometries, as well as, investigate the influence of the inlet stagnation pressure over the optimal geometries. Results showed an increase of the twice maximized cooling heat transfer rate of nearly 330 % from 300 kPa to 700 kPa. Moreover, the optimization showed a higher dependence of (d3/D)o for the lower range of inlet pressures, while the optimization is more dependent of yc,oo for higher inlet stagnation pressures.

Numerical Study of a Weight-Adjustable Buoy for Efficient Wave Energy Conversion

2021 ◽  
Author(s):  
Hao Tian ◽  
Boyang Zhou ◽  
Zengmeng Zhang ◽  
Yongjun Gong
Keyword(s):  
Natural Frequency ◽  
Incident Wave ◽  
Wave Energy ◽  
Simulation Analysis ◽  
Numerical Study ◽  
Maximum Amplitude ◽  
Wave Energy Converters ◽  
Point Tracking ◽  
Power Point ◽  
Conversion Efficiencies

Abstract Heaving motion of ocean wave is a promising renewable energy source but challenging to capture with consistent conversion efficiencies. Main issue of the varying energy extraction efficiency of wave energy converters (WEC’s) is primarily caused by the variation of incident wave frequency and amplitude. Traditional design of the WEC has to account for the extreme sea conditions, leaving the WEC to work at suboptimal regions for most of the time. Due to the loss characteristics of the fluid power components, the performance and efficiency drop rapidly when moved away from the optimal working condition. In order to improve the efficiency of WEC, the buoy needs to operate at maximum amplitude most of the time. To do so, a new buoy structure based on actively controlled fluid-air ratio is proposed. Contrast to the traditional buoy for WEC’s, which has fixed density and weight, the proposed structure is capable of weight manipulation, resulting adjustable system natural frequency. MATLAB/Simulink simulation analysis is carried out to verify the feasibility of adjusting the gas-liquid ratio inside the buoy with a water hydraulic system. To resonate with the unknown incident wave, maximum power point tracking (MPPT) algorithm is proposed to control the buoy mass with trial steps for maximizing the resonating amplitude of the buoy. Initial simulation results have shown that the proposed system is capable of adjusting the natural frequency and the MPPT algorithm can increase the amplitude of the buoy motion.

Constructal Design Applied to Geometric Shapes Analysis of Wave Energy Converters

2021 ◽  
Vol 407 ◽  
pp. 147-160
Author(s):  
Mateus das Neves Gomes ◽  
Heloiza Salvador ◽  
Felipe Magno ◽  
Amanda A. Rodrigues ◽  
Elizaldo Domingues Santos ◽  
...  
Keyword(s):  
Wave Energy ◽  
Wave Spectrum ◽  
Geometrical Shape ◽  
Peak Period ◽  
Geometric Shapes ◽  
Constructal Design ◽  
Wave Energy Converters ◽  
Ocean Wave Energy ◽  
Vof Model ◽  
Shape Influence

This paper deals with numerical simulation and the geometrical analysis of an ocean Wave Energy Converter (WEC), which has as the operating principle the Oscillating Water Column (OWC). The goal was to evaluate the geometric shape influence of the OWC chamber in the hydropneumatic power available. Therefore, four geometric shapes were analyzed: i) Rectangle (RT), ii) Trapezium (TP), iii) Inverted Trapezium (TI) and iv) Double Trapezium (DT). For this, the OWC device was subject to a JONSWAP wave spectrum with peak period (TS) equal to 7.5 s and peak wave height (HS) equal to 1.5 m. To do so, Constructal Design was employed varying the Degree Of Freedom (DOF) H1/L (ratio between the height and length of the OWC chamber entrance). The problem constraints were the entrance area and the total area of the OWC chamber that were kept constant. For the numerical solution a Computational Fluid Dynamics (CFD) code, based on the Finite Volume Method (FVM),de0 was used. The multiphase Volume of Fluid (VOF) model was applied to tackle with the water-air interaction. The results indicated that when the Rectangle (RT) geometrical shape was employed an improvement of nearly 99% was achieved.

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