Tecnalia Marine took part to the Workshop HYWEC (Hydrodynamics of Wave Energy Converters) held at BCAM (Basque Centre for Applied Mathematics) in Bilbao. Here is the presentation!! Enjoy it ;)
The following is a visual presentation of my CV, research and previous work I have been involved in at St. Anthony Falls Laboratory, University of Minnesota.
Dynamic Analysis of Power Cable in Floating Offshore Wind Turbine Franco Bontempi
Mohsen Sobhaniasl (Sapienza)
Dr. Francesco Petrini (Sapienza)
Dr. Madjid Karimirad (QUB)
Prof. Franco Bontempi (Sapienza)
The EERA Deep wind conference combines serious offshore wind research, offshore science and offshore engineering in a matter of fact form. Participation puts those at the event at the cusp of offshore research in progress and while showing the solutions needed to drive the further development of offshore wind. It is the intellectual equivalent of a good tough skiing holiday."
https://www.sintef.no/projectweb/eera-deepwind/
The following is a visual presentation of my CV, research and previous work I have been involved in at St. Anthony Falls Laboratory, University of Minnesota.
Dynamic Analysis of Power Cable in Floating Offshore Wind Turbine Franco Bontempi
Mohsen Sobhaniasl (Sapienza)
Dr. Francesco Petrini (Sapienza)
Dr. Madjid Karimirad (QUB)
Prof. Franco Bontempi (Sapienza)
The EERA Deep wind conference combines serious offshore wind research, offshore science and offshore engineering in a matter of fact form. Participation puts those at the event at the cusp of offshore research in progress and while showing the solutions needed to drive the further development of offshore wind. It is the intellectual equivalent of a good tough skiing holiday."
https://www.sintef.no/projectweb/eera-deepwind/
Fatigue Life Assessment for Power Cables in Floating Offshore Wind TurbinesFranco Bontempi
https://www.mdpi.com/journal/energies/special_issues/Wave_Tidal_Wind_Converters
Abstract: In this paper, a procedure is proposed to determine the fatigue life of the electrical cable connected to a 5MWfloating offshore wind turbine, supported by a spar-buoy at a water depth of 320 m, by using a numerical approach that takes into account site-specific wave and wind characteristics.
The efect of the intensity and the simultaneous actions of waves and wind are investigated and the outcomes for specific cable configurations are shown. Finally, the fatigue life of the cable is
evaluated. All analyses have been carried out using the Ansys AQWA computational code, which is a commercial code for the numerical investigation of the dynamic response of floating and fixed marine structures under the combined action of wind, waves and current. Furthermore, this paper applies the FAST NREL numerical code for comparison with the ANSYS AQWA results.
Keywords: wind energy; floating offshore wind turbine; dynamic analysis; fatigue life assessment; flexible power cables.
Teaching and research with MIKE by DHI - Dr Björn Elsäßer (Queen’s University...Stephen Flood
Teaching and research with MIKE by DHI - Dr Björn Elsäßer (Queen’s University Belfast).
Presented at the 2014 MIKE by DHI UK Symposium on 13th to 14th May 2014.
The Hydrodynamic Performance Examination of a New Floating Breakwater Configu...IJAEMSJORNAL
It is critical to protect coastal and offshore structures. Most current studies and scientific investigations are centered on how to protect seashore with an efficient and cost-effective system. This study involved the testing of a new floating breakwater configuration (FB). A series of experiments were carried out in the lab of The Higher Institute of Engineering (El-shorouk City) on the new model and the traditional vertical plane FB without a curved face to compare their behaviours and performance in wave attenuation. The incident, reflected, and transmitted wave heights were measured, and the coefficients of reflection, transmission, and energy dissipation were calculated using these measurements. In terms of hydrodynamic performance, the curved-face floating breakwater outperformed the traditional vertical floating breakwater, according to the study's highlights. The curved face model significantly reduced wave transmission values when compared to the traditional vertical configuration. The greater the concavity of the curve, the better the model handles waves, especially when the wave steepness is low.
Comparison of lightning return stroke channel-base current models with measur...journalBEEI
Electromagnetic pulse radiation produced around the lightning stroke channel has caused the disturbance to the microelectronic industry, especially to disturbance of high frequency to electronic systems. Lightning channel-base current function (CBC) characteristics and parameters determine lightning electromagnetic field (LEMF) results obtained on the basis of the used models. This paper evaluated and compared the measured lightning current and six lightning current-based channels models namely Bruce and Golde, Heidler, Diendorfer and Uman, Nucci, Pierce and Cianos and new current-based current (NCBC) models. In terms of the waveshape, among all the six lightning channel-based current models discussed, the models developed by Javor, Nucci and Diendorfer and Uman have showed a good agreement compared to the measured lightning current. In terms of 10-90% risetime and full width half maximum time (FWHM) comparison, NCBC and Nucci models have showed compatible comparison. However, Nucci model is not easily adjustable to different desired pulse-current waveshapes. On the other hand, NCBC model can be simplified, the values of lightning peak current and risetime can be chosen arbitrarily and independently from other parameters, and there is no need for the peak-correction factor, so that reduces the number of parameters. Therefore, the NCBC model was suggested to be used in the future in order to simulate much accurate return stroke model. This knowledge will contribute to the development of a new accurate and efficient return stroke model.
Analysis of Electric Circuit Model on Atmospheric Pressure Dielectric Barrier...AM Publications
Analysis of Electric Circuit Model on Atmospheric Pressure Dielectric Barrier Discharge (DBD) Plasma has been simulated using the Simulink-Matlab R2010a software. Plasma reactor being used as the basis to determine the parameters in the circuit is in the coaxial form made of pyrex glass with an iron rod as the active electrode and spiral copper wire as passive electrode. The reactor was filled with argon gas with the flow rate of 2 L/s. Simulation circuit model which was prepared based on a DBD equivalent circuit, operated in a voltage range of 1.0 kV to 6.0 kV for frequency of 10 kHz to 66 kHz. Electrical characterization was performed to describe the plasma discharge that occurs in the reactor. The datas of supply voltage and current, as well as voltage and current discharge, was used to determine the average power during one period. From the simulation was obtained an increase in supply and discharge currents with increasing of frequency at the same operating voltage. Discharge power has increased in a specific voltage and increased frequency. It is obtained the average discharge power for 5.5 kV of 11.28 W and 10.90 W at a frequency of 21 kHz and 24 kHz, respectively. The highest efficiency obtained from the simulation that achieved at voltage of 1 kV and frequency of 45.7 kHz is equal to 56.59%.
In this presentation, basics of solar cells, what is piezoelectricity and its application, followed by basics of thermoelectricity and its application would be discussed.
Fatigue Life Assessment for Power Cables in Floating Offshore Wind TurbinesFranco Bontempi
https://www.mdpi.com/journal/energies/special_issues/Wave_Tidal_Wind_Converters
Abstract: In this paper, a procedure is proposed to determine the fatigue life of the electrical cable connected to a 5MWfloating offshore wind turbine, supported by a spar-buoy at a water depth of 320 m, by using a numerical approach that takes into account site-specific wave and wind characteristics.
The efect of the intensity and the simultaneous actions of waves and wind are investigated and the outcomes for specific cable configurations are shown. Finally, the fatigue life of the cable is
evaluated. All analyses have been carried out using the Ansys AQWA computational code, which is a commercial code for the numerical investigation of the dynamic response of floating and fixed marine structures under the combined action of wind, waves and current. Furthermore, this paper applies the FAST NREL numerical code for comparison with the ANSYS AQWA results.
Keywords: wind energy; floating offshore wind turbine; dynamic analysis; fatigue life assessment; flexible power cables.
Teaching and research with MIKE by DHI - Dr Björn Elsäßer (Queen’s University...Stephen Flood
Teaching and research with MIKE by DHI - Dr Björn Elsäßer (Queen’s University Belfast).
Presented at the 2014 MIKE by DHI UK Symposium on 13th to 14th May 2014.
The Hydrodynamic Performance Examination of a New Floating Breakwater Configu...IJAEMSJORNAL
It is critical to protect coastal and offshore structures. Most current studies and scientific investigations are centered on how to protect seashore with an efficient and cost-effective system. This study involved the testing of a new floating breakwater configuration (FB). A series of experiments were carried out in the lab of The Higher Institute of Engineering (El-shorouk City) on the new model and the traditional vertical plane FB without a curved face to compare their behaviours and performance in wave attenuation. The incident, reflected, and transmitted wave heights were measured, and the coefficients of reflection, transmission, and energy dissipation were calculated using these measurements. In terms of hydrodynamic performance, the curved-face floating breakwater outperformed the traditional vertical floating breakwater, according to the study's highlights. The curved face model significantly reduced wave transmission values when compared to the traditional vertical configuration. The greater the concavity of the curve, the better the model handles waves, especially when the wave steepness is low.
Comparison of lightning return stroke channel-base current models with measur...journalBEEI
Electromagnetic pulse radiation produced around the lightning stroke channel has caused the disturbance to the microelectronic industry, especially to disturbance of high frequency to electronic systems. Lightning channel-base current function (CBC) characteristics and parameters determine lightning electromagnetic field (LEMF) results obtained on the basis of the used models. This paper evaluated and compared the measured lightning current and six lightning current-based channels models namely Bruce and Golde, Heidler, Diendorfer and Uman, Nucci, Pierce and Cianos and new current-based current (NCBC) models. In terms of the waveshape, among all the six lightning channel-based current models discussed, the models developed by Javor, Nucci and Diendorfer and Uman have showed a good agreement compared to the measured lightning current. In terms of 10-90% risetime and full width half maximum time (FWHM) comparison, NCBC and Nucci models have showed compatible comparison. However, Nucci model is not easily adjustable to different desired pulse-current waveshapes. On the other hand, NCBC model can be simplified, the values of lightning peak current and risetime can be chosen arbitrarily and independently from other parameters, and there is no need for the peak-correction factor, so that reduces the number of parameters. Therefore, the NCBC model was suggested to be used in the future in order to simulate much accurate return stroke model. This knowledge will contribute to the development of a new accurate and efficient return stroke model.
Analysis of Electric Circuit Model on Atmospheric Pressure Dielectric Barrier...AM Publications
Analysis of Electric Circuit Model on Atmospheric Pressure Dielectric Barrier Discharge (DBD) Plasma has been simulated using the Simulink-Matlab R2010a software. Plasma reactor being used as the basis to determine the parameters in the circuit is in the coaxial form made of pyrex glass with an iron rod as the active electrode and spiral copper wire as passive electrode. The reactor was filled with argon gas with the flow rate of 2 L/s. Simulation circuit model which was prepared based on a DBD equivalent circuit, operated in a voltage range of 1.0 kV to 6.0 kV for frequency of 10 kHz to 66 kHz. Electrical characterization was performed to describe the plasma discharge that occurs in the reactor. The datas of supply voltage and current, as well as voltage and current discharge, was used to determine the average power during one period. From the simulation was obtained an increase in supply and discharge currents with increasing of frequency at the same operating voltage. Discharge power has increased in a specific voltage and increased frequency. It is obtained the average discharge power for 5.5 kV of 11.28 W and 10.90 W at a frequency of 21 kHz and 24 kHz, respectively. The highest efficiency obtained from the simulation that achieved at voltage of 1 kV and frequency of 45.7 kHz is equal to 56.59%.
In this presentation, basics of solar cells, what is piezoelectricity and its application, followed by basics of thermoelectricity and its application would be discussed.
Similar to HYWEC (Hydrodynamics of Wave Energy Converters) Workshop at BCAM April 3-7, 2017 (20)
Francesco Boscolo, member of Tecnalia Offshore Energy Area, presents at FOWT 2018 conference in Marseille a methodology for the design of an umbilical cable for floating offshore platforms, based on static and dynamic analysis in a time domain approach, in order to get a significative time-consuming reduction in the design stage.
TECNALIA IN WAVE ENERGY SCOTLAND ANNUAL CONFERENCE 2017
François-Xavier Faÿ and Pablo Ruiz-Minguela represented TECNALIA in the Wave Energy Scotland Annual Conference held on 28th November at the John McIntyre Conference Centre, Edinburgh. The WES Annual Conference is a major networking event to help wave energy technology companies to share their ideas.
Aware of the challenges raised by the topic of control in wave energy, WES is currently supporting a control system programme and yet has awarded 13 stage 1 projects (650k€). As lead contractor of one of the projects in competition, TECNALIA displayed a poster describing the concept.
The project dubbed WEETICS (Wave Energy Enhancement Through Innovative Control System) is a multilayer control architecture aiming at evaluating the best control action according to both internal and external conditions, as well as long term effects that can affect the system reliability. Not only this control system aims to increase the WEC performance but also to bring intelligence in order to improve availability, survivability and finally drive down the LCOE. The 1st stage of the project focuses on assessing the requirements and needs in order to ensure proper definition of the 3 layers. The solution is thought to be applicable to a wide range of WECs and PTO concepts, targeting the most mature technologies currently in development.
Marine Power Systems (MPS) has published a report outlining the potential for wave power to contribute to 10% of global electricity demand by 2050.
The report titled Making Wave Power Work provides an analysis of the economic and environmental potential that wave power offers both the UK and the rest of the world.
It calls on industry and trade bodies to join up their communications around the 10% target, and businesses and governments to ramp up steady financial support and policy stability. (Source: http://tidalenergytoday.com/2017/06/28/mps-calls-for-10-wave-energy-target-by-2050/)
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Cosmetic shop management system project report.pdfKamal Acharya
Buying new cosmetic products is difficult. It can even be scary for those who have sensitive skin and are prone to skin trouble. The information needed to alleviate this problem is on the back of each product, but it's thought to interpret those ingredient lists unless you have a background in chemistry.
Instead of buying and hoping for the best, we can use data science to help us predict which products may be good fits for us. It includes various function programs to do the above mentioned tasks.
Data file handling has been effectively used in the program.
The automated cosmetic shop management system should deal with the automation of general workflow and administration process of the shop. The main processes of the system focus on customer's request where the system is able to search the most appropriate products and deliver it to the customers. It should help the employees to quickly identify the list of cosmetic product that have reached the minimum quantity and also keep a track of expired date for each cosmetic product. It should help the employees to find the rack number in which the product is placed.It is also Faster and more efficient way.
Courier management system project report.pdfKamal Acharya
It is now-a-days very important for the people to send or receive articles like imported furniture, electronic items, gifts, business goods and the like. People depend vastly on different transport systems which mostly use the manual way of receiving and delivering the articles. There is no way to track the articles till they are received and there is no way to let the customer know what happened in transit, once he booked some articles. In such a situation, we need a system which completely computerizes the cargo activities including time to time tracking of the articles sent. This need is fulfilled by Courier Management System software which is online software for the cargo management people that enables them to receive the goods from a source and send them to a required destination and track their status from time to time.
Democratizing Fuzzing at Scale by Abhishek Aryaabh.arya
Presented at NUS: Fuzzing and Software Security Summer School 2024
This keynote talks about the democratization of fuzzing at scale, highlighting the collaboration between open source communities, academia, and industry to advance the field of fuzzing. It delves into the history of fuzzing, the development of scalable fuzzing platforms, and the empowerment of community-driven research. The talk will further discuss recent advancements leveraging AI/ML and offer insights into the future evolution of the fuzzing landscape.
CFD Simulation of By-pass Flow in a HRSG module by R&R Consult.pptxR&R Consult
CFD analysis is incredibly effective at solving mysteries and improving the performance of complex systems!
Here's a great example: At a large natural gas-fired power plant, where they use waste heat to generate steam and energy, they were puzzled that their boiler wasn't producing as much steam as expected.
R&R and Tetra Engineering Group Inc. were asked to solve the issue with reduced steam production.
An inspection had shown that a significant amount of hot flue gas was bypassing the boiler tubes, where the heat was supposed to be transferred.
R&R Consult conducted a CFD analysis, which revealed that 6.3% of the flue gas was bypassing the boiler tubes without transferring heat. The analysis also showed that the flue gas was instead being directed along the sides of the boiler and between the modules that were supposed to capture the heat. This was the cause of the reduced performance.
Based on our results, Tetra Engineering installed covering plates to reduce the bypass flow. This improved the boiler's performance and increased electricity production.
It is always satisfying when we can help solve complex challenges like this. Do your systems also need a check-up or optimization? Give us a call!
Work done in cooperation with James Malloy and David Moelling from Tetra Engineering.
More examples of our work https://www.r-r-consult.dk/en/cases-en/
Saudi Arabia stands as a titan in the global energy landscape, renowned for its abundant oil and gas resources. It's the largest exporter of petroleum and holds some of the world's most significant reserves. Let's delve into the top 10 oil and gas projects shaping Saudi Arabia's energy future in 2024.
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Learn about the cost savings, reduced environmental impact, and minimal disruption associated with trenchless technology. Discover detailed explanations of popular techniques such as pipe bursting, cured-in-place pipe (CIPP) lining, and directional drilling. Understand how these methods can be applied to various types of infrastructure, from residential plumbing to large-scale municipal systems.
Ideal for homeowners, contractors, engineers, and anyone interested in modern plumbing solutions, this guide provides valuable insights into why trenchless pipe repair is becoming the preferred choice for pipe rehabilitation. Stay informed about the latest advancements and best practices in the field.
Overview of the fundamental roles in Hydropower generation and the components involved in wider Electrical Engineering.
This paper presents the design and construction of hydroelectric dams from the hydrologist’s survey of the valley before construction, all aspects and involved disciplines, fluid dynamics, structural engineering, generation and mains frequency regulation to the very transmission of power through the network in the United Kingdom.
Author: Robbie Edward Sayers
Collaborators and co editors: Charlie Sims and Connor Healey.
(C) 2024 Robbie E. Sayers
HYWEC (Hydrodynamics of Wave Energy Converters) Workshop at BCAM April 3-7, 2017
1. Challenges in the hydrodynamics
modelling of wave energy converters
Vincenzo Nava
BCAM Workshop Hydrodynamics of wave energy converters
Bilbao, 3-7 April 2017
Image from the website of OPERA H2020 project,
courtesy of EVE
Screenshot from Compass
Youtube Video
3. BCAM Workshop Hydrodynamics of wave energy converters
Bilbao, 3-7 April 2017
Why Harnessing Energy From Oceans?
3 ▌
Credits
the data originate from the ECMWF WAM model archive and are calibrated and corrected by Fugro OCEANOR against a global buoy
and Topex satellite altimeter database).
4. BCAM Workshop Hydrodynamics of wave energy converters
Bilbao, 3-7 April 2017
How can we get Energy From Oceans?
4 ▌
Souce(s)
Figure inspired from
Peñalba, M., Ringwood, J. V., A Review of Wave-to-Wire Models for Wave Energy Converters, Energies 2016, 9(7), 506;
doi:10.3390/en9070506
WAVE
RESOURCE
ELECTRIC
GENERATOR
WAVE
ENERGY
CONVERTER
POWER
TAKE OFF
POWER
CONVERSION
GRID
ABSORPTION
FPTO
x, x, x T
ω
i
V
Pout
TRANSMISSION GENERATION CONDITIONING
Oscillating Water Column (OWC)
Overtopping Devices
Oscillating Bodies
(Point Absorbers & Surge Devices)
5. BCAM Workshop Hydrodynamics of wave energy converters
Bilbao, 3-7 April 2017
A more precise modelling of the
hydrodynamics will improve:
Why numerical models are needed to simulate the FSI?
5 ▌
POWER
PRODUCTION
FORCES,
DISPLACEMENTS,
STRESSES AND
DEFORMATIONS
OVERTOPPING
OPTIMISATION OF
SHAPES, LOSSES,
ETC…
WAVE PROPAGATION
ENVIRONMENTAL
IMPACTS
ECONOMIC
ASSESSMENTS
SURVIVABILITY
IMPACTS ON
THE
ENVIROMENT
6. BCAM Workshop Hydrodynamics of wave energy converters
Bilbao, 3-7 April 2017
Top FIVE Challenges
1.
2.
3.
4.
5. WAVE PROPAGATION
7. BCAM Workshop Hydrodynamics of wave energy converters
Bilbao, 3-7 April 2017
Reduction of Energy – Using TMA spectra
7 ▌
Source
A. Sinha, D. Karmakar, and C. Guedes Soares, “Shallow water effects on wave energy converters with hydraulic power take-off system,”
Int. J. Ocean Clim. Syst., vol. 7, no. 3, pp. 108–117, 2016.
8. BCAM Workshop Hydrodynamics of wave energy converters
Bilbao, 3-7 April 2017
Modeling devices with Mike 21
8 ▌
Source
E. Angelelli and B. Zanuttigh, “A farm of wave activated bodies for coastal protection purposes,” Coast. Eng. Proc., vol. 1, no. 33, p. 68,
2012.
M. Folley et al., “A review of numerical modelling of wave energy converter arrays,” in ASME 2012 31st International Conference on
Ocean, Offshore and Arctic Engineering, 2012, pp. 535–545.
“Boussinesq models are not capable of
modelling the hydrodynamics of a moving
device.
They may be used to model device
characteristics, such as wave transmission
reflection and absorption.
If radiation characteristics are known, these
may be included by use of an internal
generation line, although this may become
cumbersome when more than 1 WEC is
considered and, for this reason, their use
warrants caution.”
9. BCAM Workshop Hydrodynamics of wave energy converters
Bilbao, 3-7 April 2017
Top FIVE Challenges
1.
2.
3.
4. VALIDATION OF MODELS
5. WAVE PROPAGATION
10. BCAM Workshop Hydrodynamics of wave energy converters
Bilbao, 3-7 April 2017
How validate and verify models?
10 ▌
• Code-to-code verification
EXAMPLE: Task 10 – OES – Methodology
Modeling case studies, as for example a heaving sphere (decay tests, regular
waves tests, irregular wave tests)
Review the models
o Model a WEC
o Compare with existing test data
11. BCAM Workshop Hydrodynamics of wave energy converters
Bilbao, 3-7 April 2017
How validate and verify models?
11 ▌
• Experimental Data
Source
Percher, A., Kofoed, J.P., Handbook of Ocean Wave Energy, 2016, Springer
12. BCAM Workshop Hydrodynamics of wave energy converters
Bilbao, 3-7 April 2017
12 ▌
Performance of WECs will normally be scaled using Froude similitude.
Tests with large scales are recommended when scale effects are envisaged.
Important factors in energy conversion that are not addressed by standard scaling
procedures include, but are not limited to, the effects listed below:
• The power output of devices utilising a pneumatic power take off is related to the
compressibility of the air, which is dictated by atmospheric pressure and the
absolute temperature of atmosphere. Therefore, the stiffness of the air “spring”
will not be scaled correctly using Froude similarity if geometric similarity is
maintained.
• In small - scale model tests, viscous damping and in particular damping associated
with vortex shedding from sharp edges cannot be scaled appropriately with
Froude similarity and may be overestimated.
Source
ITTC – Recommended Guidelines, Wave Energy Converter Model Test Experiments, 2014
Weber, J.,2007,“Representation of non-linear aero-thermodynamic effects during small scale physical modelling of OWC WECs”,
Proceedings,7th European Wave and Tidal Energy Conference(EWTEC 2007), Porto,Portugal
Importance of scale – Scaling Law
13. BCAM Workshop Hydrodynamics of wave energy converters
Bilbao, 3-7 April 2017
Importance of scale – Instrumentation and Indirect Measurements
13 ▌
Source
C. Ruzzo, G. Failla, M. Collu, V. Nava, V. Fiamma, and F. Arena, “Operational Modal Analysis of a Spar-Type Floating Platform Using
Frequency Domain Decomposition Method,” Energies, vol. 9, no. 11, p. 870, Oct. 2016.
Measurements of:
• Displacements / Velocities / Accelerations
• Line Tensions
• Wave Characteristics
• Overtopping
Use of indirect measurements,
especially with data in sea.
Development of algorithms for
indirect measurements, also from
other sectors. For example, FDD for
modal characteristics (from the
Structural health monitoring
Sector).
14. BCAM Workshop Hydrodynamics of wave energy converters
Bilbao, 3-7 April 2017
Top FIVE Challenges
1.
2.
3. MODELING ARRAY EFFECTS
4. VALIDATION OF MODELS
5. WAVE PROPAGATION
15. BCAM Workshop Hydrodynamics of wave energy converters
Bilbao, 3-7 April 2017
Why arrays?
15 ▌
Deploying arrays of
ocean energy devices
would increase the
profitability of the
investment
Image courtesy of
16. BCAM Workshop Hydrodynamics of wave energy converters
Bilbao, 3-7 April 2017
How to model array effects?
16 ▌
Source
H. Day et al., “Hydrodynamic modelling of marine renewable energy devices: A state of the art review,” Ocean Eng., vol. 108, pp. 46–
69, Nov. 2015.
M. Folley et al., “A review of numerical modelling of wave energy converter arrays,” in ASME 2012 31st International Conference on
Ocean, Offshore and Arctic Engineering, 2012, pp. 535–545.
•Point-absorber method
(diameters smaller than wavelenghts and
interdistances - diffraction of radiated and
diffracted waves from each device by others in
the array is neglected)
•Plane-wave method
(spacing between axisymmetric absorbers is
large compared to the incident wavelength –
diffraction is taken into account)
•Multiple Scattering Method
(radiation and diffraction taken into account as
succession of distinct scattering events)
•Direct Matrix Method
(the amplitudes of all scattered waves
simultaneously without the need for
iteration, using a single body solution)
SPH
17. BCAM Workshop Hydrodynamics of wave energy converters
Bilbao, 3-7 April 2017
Some results
17 ▌
Personal Note: when fully designing an
array of heaving point
absorbers, most probably
the layout would depend
on other subsystems
rather than on the
hydrodynamic impacts
Source
Peñalba, M., Touzon, I., Lopez Mendia, J., Nava, V., A numerical study on the hydrodynamic impact of device slenderness and array size
in wave energy farms in realistic wave climates, 2017, under review
18. BCAM Workshop Hydrodynamics of wave energy converters
Bilbao, 3-7 April 2017
Some results
18 ▌
Source
E. Renzi, A. Abdolali, G. Bellotti, and F. Dias, “Wave-power absorption from a finite array of oscillating wave surge converters,” Renew.
Energy, vol. 63, pp. 55–68, Mar. 2014.
19. BCAM Workshop Hydrodynamics of wave energy converters
Bilbao, 3-7 April 2017
Development of Tools
19 ▌
DTOcean is the acronym for an European FP7
project and it stands for
Optimal Design Tools for Ocean Energy Arrays
Hydrodynamics
modeled using semi-
analytical methods
BEM NEMOH + DMM
20. BCAM Workshop Hydrodynamics of wave energy converters
Bilbao, 3-7 April 2017
Top FIVE Challenges
1.
2. VISCOUS EFFECTS AND EXTREME LOADS
3. MODELING ARRAY EFFECTS
4. VALIDATION OF MODELS
5. WAVE PROPAGATION
21. BCAM Workshop Hydrodynamics of wave energy converters
Bilbao, 3-7 April 2017
Sloshing
21 ▌
Source
Y. Zhang, Q.-P. Zou, and D. Greaves, “Air–water two-phase flow modelling of hydrodynamic performance of an oscillating water column
device,” Renew. Energy, vol. 41, pp. 159–170, May 2012.
It is difficult to extract
energy from sloshing
frequency, so they should be
avoided.
22. BCAM Workshop Hydrodynamics of wave energy converters
Bilbao, 3-7 April 2017
Vortex Formation
22 ▌
Source
Y. Zhang, Q.-P. Zou, and D. Greaves, “Air–water two-phase flow modelling of hydrodynamic performance of an oscillating water column
device,” Renew. Energy, vol. 41, pp. 159–170, May 2012.
The formation of the vortex in front of and
behind the front wall of the air chamber and
evolution of the air vortex can be seen
clearly which is a good indicator of energy
loss.
23. BCAM Workshop Hydrodynamics of wave energy converters
Bilbao, 3-7 April 2017
Vortex Induced Vibration / Motions
23 ▌
Source
Z.-S. Chen and W.-J. Kim, “Numerical investigation of vortex shedding and vortex-induced vibration for flexible riser models,” Int. J. Nav.
Archit. Ocean Eng., vol. 2, no. 2, pp. 112–118, Jun. 2010.
If the structure is flexible or flexibly mounted,
these vortices may cause vibrations, leading to
stresses and fatigue damage. This motion of the
body influences, in turn, the vortex formation
process, establishing a feedback mechanism that
may lead to stable or unstable dynamic equilibria.
On the hull:
- They increase the global loads
- They may increase the offset (drag effect)
On the moorign lines:
- They may affect fatigue life of the line
The disagreement between numerical and
experimental observations attributes much to the
underestimation of multimodal vibration state by
numerical method.
24. BCAM Workshop Hydrodynamics of wave energy converters
Bilbao, 3-7 April 2017
Vortex Induced Vibration / Motions
24 ▌
Source
M. S. Triantafyllou, R. Bourguet, J. Dahl, and Y. Modarres-Sadeghi, “Vortex-Induced Vibrations,” in Springer Handbook of Ocean
Engineering, Springer, 2016, pp. 819–850.
On the hull:
- They increase the global loads
- They may increase the offset (drag effect)
On the moorign lines:
- They may affect fatigue life of the line
Higher harmonic components of strain and
acceleration are significant. Fatigue damage
calculations, by taking into account the higher
harmonic components, give fatigue damage
values of up to one order of magnitude larger
than those calculated based on only first-
harmonic signals.
25. BCAM Workshop Hydrodynamics of wave energy converters
Bilbao, 3-7 April 2017
Extreme Wave Loads
25 ▌
Source
J. Westphalen, “Extreme wave loading on offshore wave energy devices using cfd,” 2011.
26. BCAM Workshop Hydrodynamics of wave energy converters
Bilbao, 3-7 April 2017
Top FIVE Challenges
1. NONLINEARITIES AND COUPLING
2. VISCOUS EFFECTS AND EXTREME LOADS
3. MODELING ARRAY EFFECTS
4. VALIDATION OF MODELS
5. WAVE PROPAGATION
27. BCAM Workshop Hydrodynamics of wave energy converters
Bilbao, 3-7 April 2017
Mooring Lines Effects
27 ▌
Source
S.-H. Yang, J. W. Ringsberg, E. Johnson, Z. Hu, and J. Palm, “A comparison of coupled and de-coupled simulation procedures for the
fatigue analysis of wave energy converter mooring lines,” Ocean Eng., vol. 117, pp. 332–345, May 2016.
28. BCAM Workshop Hydrodynamics of wave energy converters
Bilbao, 3-7 April 2017
Parametric Roll – Mathieu/Hill Instability
28 ▌
Source
K. Tarrant and C. Meskell, “Investigation on parametrically excited motions of point absorbers in regular waves,” Ocean Eng., vol. 111,
pp. 67–81, Jan. 2016.
29. BCAM Workshop Hydrodynamics of wave energy converters
Bilbao, 3-7 April 2017
Parametric Roll – Mathieu/Hill Instability
29 ▌
Source
H. Mao and H. Yang, “Parametric pitch instability investigation of Deep Draft Semi-submersible platform in irregular waves,” Int. J. Nav.
Archit. Ocean Eng., vol. 8, no. 1, pp. 13–21, Jan. 2016.
The phenomenon happens in real seas: which are numerical tools to learn more
about its occurrence?
30. BCAM Workshop Hydrodynamics of wave energy converters
Bilbao, 3-7 April 2017
Lessons Learnt
1) Describing the problem properly
and identifying the outcomes
Problem statement stage is important, in order to focus on the right
physics to study.
31. BCAM Workshop Hydrodynamics of wave energy converters
Bilbao, 3-7 April 2017
Lessons Learnt
2) Importance of using the appropriate
numerical model for solving the
problem
Risks:
a. Unneeded
computational
burden
b. Not answering to the
questions
32. BCAM Workshop Hydrodynamics of wave energy converters
Bilbao, 3-7 April 2017
Lessons Learnt
3) Interpreting the results of the
experimental / numerical study in
order to “bark at the right tree”
The results of a good
experimental campaign or
numerical test can be jeopardised
by a wrong understanding of
what’s going on.
33. BCAM Workshop Hydrodynamics of wave energy converters
Bilbao, 3-7 April 2017
Lessons Learnt
4) All the problems are important, but
some problems are more important
than others
Developers have identified
different priorities for the
problems to be solved through
their experience.
Moreover, sometimes we look
at a problem from a wrong
perspective.
34. THANKS FOR YOUR ATTENTION
Vincenzo Nava
vincenzo.nava@tecnalia.com
vnava@bcamath.org
BCAM Workshop Hydrodynamics of wave energy converters
Bilbao, 3-7 April 2017