Appendage and Viscous Forces for Ship Motions in Waves
DEFENCE RESEARCH AND DEVELOPMENT ATLANTIC DARTMOUTH (CANADA)
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This report describes the prediction of appendage and viscous forces in Defence Research and Development Canada DRDC Atlantics ShipMo3D library for ship motions in waves. Previously, the ShipMo3D library considered only hull forces due to potential flow. Inclusion of appendage and viscous forces is essential for accurate prediction of ship sway, roll, and yaw motions. Appendage forces are caused by added mass, lift, and viscous effects. Hull viscous forces are also important and are included in the present treatment. This report introduces a method for including appendages in hull radiation and diffraction computations by representing appendages using dipole panels. Computations for a naval destroyer have indicated that inclusion of appendages in hull radiation and diffraction computations has a negligible effect on predicted motions thus, hull and appendage forces can be evaluated separately without affecting accuracy of motion predictions. Comparisons of predictions with experiments for a steered warship model in regular waves show good agreement. Future work will incorporate hull lift forces in ship motion predictions. 7 tables, 43 figures, 29 refs.
- Physical and Dynamic Oceanography
- Theoretical Mathematics
- Marine Engineering
- Fluid Mechanics