A Linearized Free-Surface Method for Prediction of Unsteady Ship Maneuvering.

Abstract

Maneuvering prediction tools are valuable resources for naval and commercial ship designers. They estimate the ability of a ship to maintain or alter course. This enables designers to characterize the maneuvering performance of multiple conceptual hull forms and select an optimal design. A novel maneuvering prediction method is presented in this thesis. It is an unsteady Reynolds-averaged Navier-Stokes (URANS) approach that includes wave effects with linear free-surface boundary conditions. Therefore, it is a single-phase approach to solving multiphase problems. The solution of the URANS equations captures the viscous effects that are highly important in maneuvering due to the complex fluid interactions between the hull, propellers, and rudders. The linearized free-surface approximation accounts for first-order wave effects while reducing the necessary extents of the computational domain and the level of grid refinement required by nonlinear computational fluid dynamics (CFD) solvers. These simplifications lead to a substantial improvement in computational efficiency with respect to nonlinear methods, while retaining accuracy and empowering naval architects to obtain results earlier in the design cycle.