A new radiation condition for ships travelling with very low forward speed

Yuan, Zhi-Ming and Incecik, Atilla and Jia, Laibing (2014) A new radiation condition for ships travelling with very low forward speed. Ocean Engineering, 88. pp. 298-309. ISSN 0029-8018

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    Abstract

    The 3-D Rankine source method is becoming a very popular method for the seakeeping problem, especially when marine vessels are travelling with forward speed. However, this method requires an accurate radiation condition to ensure that the waves propagate away from the ship. Considerable effort has been expanded for the accurate formulation of the radiation condition when a ship travels at the moderate to high speed range, and significant progress has been made in the last few decades when the Brard number τ is greater than 0.25. But for the very low forward speed problem (τ<0.25), the ordinary radiation condition will not be valid since the scattered waves will propagate ahead of the vessel. The primary purpose of the present study which is to be presented in this paper is to investigate the formulation of a new radiation condition which can account for the very low forward speed problem. To verify this new radiation condition, a Wigley III hull has been modelled by using the 3-D panel method. The hydrodynamic coefficients and the wave pattern of the vessel at zero speed and travelling with very low and medium forward speeds are calculated separately. From the comparisons of the present results with experimental measurements, it can be concluded that the new radiation condition can accurately predict the hydrodynamic properties of vessels travelling with low to medium forward speed or stationary in waves.