Comparison of two numerical models for the prediction of parametric roll resonance in regular waves

Ahmed, T.M., Hudson, D.A. and Temarel, P. (2010) Comparison of two numerical models for the prediction of parametric roll resonance in regular waves. PRADS 2010: 11th International Symposium on Practical Design of Ships and Other Floating Structures, Rio de Janeiro, Brazil. 19 - 24 Sep 2010. 10 pp .

Abstract

In this paper, two non-linear time domain numerical methods are used for the prediction of parametric roll resonance in regular waves encountered at various headings. Method (I) is a 2.5-DoF model in heave, roll and pitch, where heave and pitch motions are evaluated simultaneously, and independently of roll and are based on the mean wetted surface. Subsequently, the 1-DoF equation of motion in roll is solved in the time domain, with parametric excitation terms accounted for as third order non-linearities, defined in terms of heave-pitch-wave profile coupling with roll. Method (II) is a 4-DoF model in sway, heave, roll and pitch. The non-linear incident wave and hydrostatic restoring forces/moments are evaluated considering the instantaneous waterline. The radiation/diffraction forces and moments are expressed in terms of convolution integrals through impulse response functions that are based on the mean wetted surface, using 3D potential flow analysis (pulsating source). Methods (I) and (II) are applied to the ITTC-A1 containership and are validated by comparison to experimental data provided through the SAFEDOR Benchmark Study.

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Contributors

Author: D.A. Hudson

Author: P. Temarel

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