| A boundary value problem defining potential flow around three-dimensional ship hulls moving in confined channels is formulated within the context of linear theory. No restriction is imposed on either channel or hull geometry and the hull boundary condition is satisfied exactly. On the free surface, a double body approximation is employed assuming that the ship is advancing slowly. A boundary element method (BEM) is employed to solve the problem numerically. The accuracy of the model and the validity of the underlying assumptions are tested by comparing the model predictions against available experimental data as well as theoretical results. A parametric study is conducted to determine the effects of channel depth, width, bank slope and eccentricity on squat. Moreover, bank force and moment for two types of vessels are computed for several asymmetric positioning in the channel and the results are compared against experimental data available in the literature. The proposed model has an advantage over the existing formulas for squat computations applicable to on-center operations in that the channel and hull form can be accurately incorporated in the predictions. Furthermore, since the problem is formulated in three-dimensions, any possibility of cross-flow beneath the hull is included in the formulation. Therefore, squat and bank effects associated with off-center ship operations can be simulated properly by means of the proposed model. |
