Aiming at time-domain hydrodynamic analysis of a ship with forward speed, the multi-domain higher order boundary element method (MDHOBEM) was established. With an imaginary control surface, the computation domain was divided into the inner and outer domain. In the inner domain, the Rankine panel method was applied while in the outer domain the free surface Green’s function was applied. The initial boundary problems in the inner and outer domains were solved together. To satisfy different working condi⁃ tions, improvements were made in the inner domain, outer domain and wave excitations for the accuracy and computation efficiency of MDHOBEM. In the inner domain, the nonlinear boundary conditions were re-de⁃ rived by considering influence of incident waves on the diffraction-radiation problem, which improves the ac⁃ curacy of MDHOBEM in motion calculation of large-amplitude waves. In the outer domain, the vertical inte⁃ gral of free surface Green’s function was proposed to improve the convergence, stability and efficiency of the panel integral of Green’s function. In the wave excitations, the high order spectral (HOS) method was adopt⁃ ed to simulate incident wave fields, which considers the nonlinearity of waves field itself and improves the ability of MDHOBEM in capturing nonlinear phenomenon. The motions of C11 container ship in large ampli⁃ tude waves were calculated to validate the improvement of accuracy due to the inner aspect improvement. Added wave resistance of S175 ship was studied to validate the improvement in efficiency and stability due to the outer aspect improvement. The motions of S175 in linear/nonlinear waves were calculated to validate the influence of nonlinear incident wave on ship motions. The parametric roll of one tumble home hull was studied to validate the improvement of MDHOBEM in capturing nonlinear phenomenon due to wave excita⁃ tion improvement. The multi-domain method with multi-level improvement was established to support time domain hydrodynamic analysis for different working conditions with math model and program codes. © 2023 China Ship Scientific Research Center. All rights reserved.
