TY - CONF
TI - Third-Order First-Harmonic Wave Excitation Forces on Spherical Geometries
AU - Tan, B
AU - Orszaghova, J
AU - Wolgamot, H
AU - Kurniawan, A
AU - Todalshaug, J
T2 - 39th International Workshop on Water Waves and Floating Bodies (IWWWFB Scotland, 2024)
AB - Higher-order wave-structure interactions are generally investigated to improve the estimation of super- and sub-harmonic forcing relevant to high-frequency structural responses in fixed offshore structures and low-frequency motion responses of soft-moored floating structures. However, far fewer studies have been conducted on higher-order interactions within the wave frequency range which is of primary interest to wave energy devices tuned to resonate within this range. We experimentally investigate nonlinear effects in first-harmonic wave excitation forces on a fixed sphere of radius a = 0.125 m, representative of an archetypal heaving point absorber at reduced scale. The experiments were conducted in a large wave flume at the Coastal and Offshore Research Laboratory at the University of Western Australia. To excite the response, we used incident focused wave groups derived from underlying JONSWAP spectra representative of a range of operational conditions. To probe nonlinearities, we utilised wave groups with progressively higher focus amplitudes. We considered three peak periods and a range of model drafts, but for brevity only show a subset of the results here. We find that third-order first harmonic forces are readily apparent and for heave in longer waves can be as large as 8% of the peak force in energetic operational conditions. This is primarily induced by the cubic relationship between the spherical cap’s volume and draft. 
DA - 2024/04//
PY - 2024
SP - 4
PB - IWWWFB
UR - http://www.iwwwfb.org/Workshops/39.htm
LA - English
KW - Wave
KW - Point Absorber
KW - Oscillating Wave Surge Converter
ER -