Kim Nielsen, Danish Wave Power Aps, Bredevej 2, DK-2830 Virum
ABSTRACT
This paper will describe the numerical design models developed by DWP and ES-Consult as part of the Off-shore Wave Energy Converter project OWEC-I supported by the European Union under the JOULE initiative. The OWEC-I project is coordinated by DWP and comprised of twenty participating institutions from seven European countries and the project builds upon work carried out in previous national programs.
Offshore Wave Power Plants composed of float pump systems, has been investigated Modeling techniques required to provide reliable methods for the predicted hydrodynamic behavior of the floats, their performance has been assessed and standardized criteria and techniques for the design has been provided.
The systems investigated and the numerical time domain models developed will be described. The DWP/ES-Consult design models include both heave and surge motion of the device motion. The hydrodynamics are based on the long wave approximation of wave exiting forces as well as nonlinear drag and lift-forces, limits for the buoyancy force and variation of added mass with submergence are included in the calculations [1].
The numerical models developed by DWP/ES-Consult are intended as tools for the structural design. The results in medium waves are compared to more exact hydrodynamic models (heave only) developed at Chalmars University and at NTH Norwegian Technical University. Results are compared to model tests and real sea measurements.
The design of the float geometry's and power takeoff, has not been optimized. The scope has been to compare and provide tolls and guidelines for time domain modeling of offshore wave energy converters as a basis for further optimization.
MODELLING THE EFFECT OF SHELTER IN THE MODIFICATION OF WAVES FROM THE OPEN SEA TO NEAR-SHORE
H. Oliveira-Pires and Fernando Carvalho, Instituto de Meteorologia, Rua Cao Aeroporto, 1700 LISBOA, PORTUGAL
Teresa Pontes, INETI, Estrada do Paso do Lumiar, 1699 LISBOA CODEX, PORTUGAL
ABSTRACT
An efficient method has been developed to compute the wave conditions in sheltered areas from the open sea directional spectrum using a reverse tracing wave ray model. The methodology is presented and the results are verified in two cases. One case is Porto 1 Cachorro. located in the middle of the North Atlantic, surrounded by several islands with an intricate geometry, where an European wave energy pilot plant will be constructed soon. The other case is Sines, at the west coast of Portugal, where there are two buoys deployed in close locations that provide data to test the spatial resolution of the ray model. The range of applicability of this type of ray model seems to lie at the transition between the open sea, well represented through large scale wind-wave models, and the zones close to shore where shallow water wave breaking (not represented in the model) begins to play a dominant and decisive role.
