Abstract
The problem of surface ships free to pitch and heave in regular head waves is analyzed numerically with an unsteady Reynolds averaged Navier Stokes (URANS) approach. The unsteady single-phase level set method previously developed by the authors was extended to include six degrees of freedom (6DOF) motions. The method uses rigid overset grids that move with relative motion during the computation, and the interpolation coefficients between the grids are recomputed dynamically every time the grids move. The motions in each time step are integrated implicitly using a predictor-corrector approach. An earth-based reference system is used for the solution of the fluid flow, while a ship-based reference system is used to compute the rigid-body equations of motion. Predicted results for sinkage and trim and resistance at two Froude numbers (medium, Fr = 0.28 and large, Fr = 0.41) were compared against experimental data, showing good agreement. Pitch and heave motions were computed for near-resonant cases at Fr = 0.28 and 0.41, with regular linear head waves with slope ak = 0.025 and wavelength λ = 1.5L, with L the ship length. The predicted motions compare favorably with existing experimental data. A solution for a large amplitude head wave case (ak = 0.075) was also obtained, in which the transom wave breaks and extreme motions are observed. The medium Froude number case was subject to a verification and validation analysis. A problem with two ships pitching and heaving one behind the other is demonstrated.
Original language | English |
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Pages (from-to) | 1415-1433 |
Number of pages | 19 |
Journal | Computers and Fluids |
Volume | 36 |
Issue number | 9 |
DOIs | |
State | Published - Nov 2007 |
Externally published | Yes |
Funding
This research was sponsored by the Office of Naval Research under Grant N00014-01-1-0073, with Dr. Patrick Purtell as the program manager. The computations were performed at DoD High Performance Computing Modernization Program ARSC and NAVO computing centers. Ralph Noack’s contribution to this research was made possible through support provided by the Department of Defense (DOD) High Performance Computing Modernization Program (HPCMP) Programming Environment and Training (PET) activities through Mississippi State University under the terms of Contract No. N62306-01-D-7110. The opinions expressed herein are those of the authors and do not necessarily reflect the views of the DOD or Mississippi State University.
Funders | Funder number |
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HPCMP | |
Programming Environment and Training | |
U.S. Department of Defense | |
Office of Naval Research | N00014-01-1-0073 |
Mississippi State University | N62306-01-D-7110 |