Seakeeping Analysis of a Wave-Piercing Catamaran Using URANS-Based Method

Abstract

Wave-piercing catamarans (WPCs) consist of two demihulls with wave-piercing bows that may immerse into or emerge out of the free surface when advancing in waves. Therefore, it is questionable whether linear theories like modified strip theory (STF) can precisely predict the seakeeping performance of WPCs in general cases. In this paper, the unsteady Reynolds-averaged Navier–Stokes equations (URANS) method is used to predict the pitch and heave motions of WPCs under various speeds and wave frequencies in head seas, while the STF method is employed for comparison. Furthermore, some parametric studies, such as modifying the shape of wave-piercing bows, disregarding the interaction between demihulls, neglecting the viscosity of water, and altering wave steepness, are also carried out using the URANS-based method. Comparison of numerical and experimental results shows that, under the Froude numbers of interest 4003 ≤ Fn ≤ 0065, acceptable agreement is achieved by using the URANS-based method, while only a similar trend is obtained by using the STF method at the small Froude number Fn = 003. Based on the numerical results of parametric studies, it is shown that the effects of wave steepness and forward speed on the free surface are significant, while the viscous effect is unimportant to the heave and pitch motions.