Numerical Study on Hydrodynamics of Ships with Forward Speed Based on Nonlinear Steady Wave

Abstract

In this paper, an improved potential flow model is proposed for the hydrodynamic analysis of ships advancing in waves. A desingularized Rankine panel method, which has been improved with the added effect of nonlinear steady wave-making (NSWM) flow in frequency domain, is employed for 3D diffraction and radiation problems. Non-uniform rational B-splines (NURBS) are used to describe the body and free surfaces. The NSWM potential is computed by linear superposition of the first-order and second-order steady wave-making potentials which are determined by solving the corresponding boundary value problems (BVPs). The so-called m j terms in the body boundary condition of the radiation problem are evaluated with nonlinear steady flow. The free surface boundary conditions in the diffraction and radiation problems are also derived by considering nonlinear steady flow.To verify the improved model and the numerical method adopted in the present study, the nonlinear wave-making problem of a submerged moving sphere is first studied, and the computed results are compared with the analytical results of linear steady flow. Subsequently, the diffraction and radiation problems of a submerged moving sphere and a modified Wigley hull are solved. The numerical results of the wave exciting forces, added masses, and damping coefficients are compared with those obtained by using Neumann-Kelvin (NK) flow and double-body (DB) flow. A comparison of the results indicates that the improved model using the NSWM flow can generally give results in better agreement with the test data and other published results than those by using NK and DB flows, especially for the hydrodynamic coefficients in relatively low frequency ranges.

Stability and Seakeeping of Marine Vessels

“…The book Stability and Seakeeping of Marine Vessels includes nine contributions [1][2][3][4][5][6][7][8][9] to this Special Issue published during 2020. The overall aim of the collection is to improve knowledge about the most relevant and recent topics in ship stability and seakeeping.…”

“…Furthermore, the visualization of the flooding process efficiently explains the causes of the motion responses and can improve the analysis of ship survivability. Mei et al (2020) [2] propose an improved potential flow model for the hydrodynamic analysis of ships advancing in waves. This advanced potential flow method is based on the desingularized Rankine panel method, which is improved with the added effect of nonlinear steady wave-making (NSWM) flow in the frequency domain.…”