Unsteady RANS method for surface ship boundary layer and wake and wave field

Results are reported of an unsteady Reynolds-averaged Navier-Stokes (RANS) method for simulation of the boundary layer and wake and wave field for a s urface ship advancing in regular head waves, but restrained from body motio ns. Second-order finite differences are used for both spatial and temporal discretization and a Poisson equation projection method is used for velocit y-pressure coupling. The exact kinematic free-surface boundary condition is solved for the free-surface elevation using a body-fitted/free-surface con forming grid updated in each time step. The simulations are for the model p roblem of a Wigley hull advancing in calm water and in regular head waves. Verification and validation procedures are followed, which include careful consideration of both simulation and experimental uncertainties. The steady flow results are comparable to other steady RANS methods in predicting res istance, boundary layer and wake, and free-surface effects. The unsteady fl ow results cover a wide range of Froude number, wavelength, and amplitude f or which first harmonic amplitude and phase force and moment experimental d ata are available for validation along with frequency domain, linear potent ial flow results for comparisons. The present results, which include the ef fects of turbulent flow and non-linear interactions, are in good agreement with the data and overall show better capability than the potential flow re sults. The physics of the unsteady boundary layer and wake and wave field r esponse are explained with regard to frequency of encounter and seakeeping theory. The results of the present study suggest applicability for addition al complexities such as practical ship geometry, ship motion, and maneuveri ng in arbitrary ambient waves. Copyright (C) 2001 John Wiley & Sons, Ltd.