Abstract
The Helmholtz mode and other symmetric modes of resonance of a moonpool between two heaving rectangular floating cylinders are investigated. The hydrodynamic behavior around these resonant modes is examined together with the associated mode shapes in the moonpool region. It is observed that near each of the resonance frequencies, the damping coefficient can vanish. The Helmholtz mode is characterized by a region of modest variation of added-mass value from negative to positive near the Helmholtz frequency. The peaks are, however, bounded with the cross-over point in sign corresponding to a bounded spike in damping. The higher-order resonant modes are characterized by the presence of standing waves in the moonpool, which leads to large spikes in the hydrodynamic behavior near the resonance frequencies. The Helmholtz frequency has a distinct value, while the higher-order resonances occur at fairly regular intervals of the frequency parameter, σ2(w − b)/g, where w − b is the moonpool gap. The parametric dependence of the hydrodynamic behavior on frequency and geometry is discussed.
With best wishes to my colleague and good friend, Nick Newman, on the occasion of his 70th birthday. A leader and staunch supporter of marine hydrodynamics, Nick has expanded the reach and influence of this field through his insights and publications. His contributions have been wide-ranged and his graciousness to young researchers is exemplary. May he enjoy the best of health in the years to come.
R.W. Yeung
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Yeung, R.W., Seah, R.K.M. On Helmholtz and higher-order resonance of twin floating bodies. J Eng Math 58, 251–265 (2007). https://doi.org/10.1007/s10665-006-9109-3
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DOI: https://doi.org/10.1007/s10665-006-9109-3