The Calculation Of Ship-Generated Wave And Their Actions To A Vertical Cylinder

There are three main tasks in this thesis, the calculation of the Green Function, the computing of ship-generated waves; the solution of ship-generated waves' actions on a surface-piercing vertical cylinder.In the first part, calculations have been carried out based on the Green Function given by Noblesse. Calculation results have been analyzed. The calculation results have been also given for the waves generated by a forward ship in the far field, under the assumption of a thin ship. The calculation results indicate that the oscillatory term in the Green Function is negligible far away from the ship. The introduction of waves generated by a catamaran and the ship waves reflected by the vertical river bank has been given at the end of the first part.In the second part, the boundary element method (constant panel) based on the Kelvin Source has been used to calculate the waves generated by a vertical cylinder in the current with a constant speed. Then the phenomenon of waves generated by a 'fat ship' has been computed using this method and the bow waves of a fat ship and a thin ship wave have been compared. In addition, this method can be used to solve the problem of linear waves generated by an arbitrary three-dimension body moving at a constant speed in the calm water, and the waves generated by a submarine body.At last, a surface-piercing vertical cylinder subjected to the waves caused a nearby moving ship is studied. Detailed formulation of the problem is given, which is composed of two parts: the waves generated by the moving ship (ship wave problem) and the wave field acting on the cylinder (wave action on the cylinder problem). The ship wave problem is solved by use of the thin-ship theory. A Rankine source method (constant panel) is developed to calculate the action of ship generated waves on the vertical cylinder in finite depth water. Firstly, regular wave actions on the vertical cylinder have been computed using this method and compared with the analytical solution for the purpose of testing the numerical method. Good agreements between the results obtained by the two methods are observed. Then ship-generated waves are used as incident wave fields. The diffraction wave field by the cylinder is estimated using this method. Forces and moments acting on the cylinder are estimated from the diffraction wave field. The derivatives of diffraction potential on the free surface are calculated using the 4th order Adams-Bush difference method. The analysis shows that the results have appropriately revealed the expected behaviors of such a problem.