A fast-running CFD formulation for unsteady ship maneuvering performance prediction

Maneuvering prediction tools are important resources for naval and commercial ship designers. They can enable designers to determine maneuvering characteristics of a design prior to construction or be useful in redesign if a ship is underperforming. Numerical methods allow for multiple hulls to be compared digitally, so a certain level of optimization can be achieved through evaluating trade-offs among designs before construction. In this paper, a novel maneuvering prediction method is presented that seeks to provide the accuracy available from today state-of-the-art numerical viscous-flow tools but with significantly reduced computational cost. The numerical formulation is based on the unsteady Reynolds-averaged Navier-Stokes (URANS) equations, and the unsteady ship generated waves are represented by the linear free-surface boundary conditions. The URANS equations are solved on an unstructured finite-volume discretization of the fluid domain around the hull and its appendages. The linearized free-surface approximation accounts for first-order wave effects while reducing the necessary extent of the computational domain and level of grid refinement required by fully nonlinear methods that employ an interface-capturing technique. The resulting formulation provides a marked improvement in computational efficiency with respect to nonlinear methods and can empower naval architects to obtain accurate results earlier in the design process.