Wave energy converters (WECs) usually require reactive power for increased levels of
energy conversion, resulting in the need for more complex power take-off (PTO) units, compared to
WECs that do not require reactive power. A WEC without reactive power produces much less energy,
though. The concept of Variable Shape BuoyWave Energy Converters (VSB WECs) is proposed to
allow continuous shape-change aiming at eliminating the need for reactive power, while converting
power at a high level. The proposed concept involves complex and nonlinear interactions between the
device and the waves. This paper presents a Computational Fluid Dynamics (CFD) tool that is set up
to simulate VSB WECs, using the ANSYS 2-way fluid–structure interaction (FSI) tool. The dynamic
behavior of a VSB WEC is simulated in this CFD-based Numerical Wave Tank (CNWT), in open sea
conditions. The simulation results show that the tested device undergoes a significant deformation
in response to the incoming waves, before it reaches a steady-state behavior. This is in agreement
with a low-fidelity dynamic model developed in earlier work. The resulting motion is significantly
different from the motion of a rigid body WEC. The difference in the motion can be leveraged for
better energy capture without the need for reactive power.
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