Numerical Calculation And Research Of Ship Wave-making Problem By A Raised Panel Method Based On NURBS

This thesis presents a raised panel method based on NURBS(Non- Uniform Rational B-Splines) for predicting the wave pattern and wave resistance of a ship, with forward speed, piercing the free surface of an ideal fluid.It is different from traditional panel methods that NURBS are employed not only to represent the body geometry, disturbed free surface, but also to represent the unknown source strength distribution, with all the weights on control points of NURBS set to 1.0, on panels of body surface and above free surface. NURBS make the geometry representation of the body shape and the wave pattern more precise. Raised panels above the free surface produce less numerical dispersion error, need less CPU consumption and are helpful, combined with collocation point shifting upstream, for satisfying the radiation condition numerically.Taking notice of the advantages and disadvantages of those surface-fitting methods in NURBS such as the traditional way using hnots as interpolation points, the least square method and the Skinning method, a simple and efficient method conforming to the theorem of Schoenberg-Whitney is presented,and encouraging numerical results are achived.As applications of the method, the linear wave making problems of Wigley hull and Series 60 hull are solved, with less collocation-points than that in traditional panel method, and the Kelvin wave-patterns calculated are in accord with the test data. Reasonable Kelvin wave-pattern and wave resistance of a high-speed round-bulge ship with transom stern are obtained by enforcing a condition, resembling Kutta-type condition, of smooth flow detachment at the transom stern. In addition to that, the linear solution of a catamaran is also presented.