Research on pitching of ship in shallow narrow fairways

Abstract

The article analyzes the existing calculation methods for determining the hydrodynamic characteristics of the ship's wobble in conditions compressed by the vertical boundaries of the fairway (in the channel, parallel to the berth).Correct determination of the characteristics of the ship's wobble in the conditions of a compressed fairway will ensure the safety of these works and reduce the likelihood of damage to ships.It has been found that sailing in fairway conditions, limited not only by depth but also by rigid vertical boundaries (for example, a canal parallel to the berth), leads to a significant change in the seaworthiness of vessels.In contrast to the rocking of a ship in unlimited space, the amount of work devoted to solving the problem of hydrodynamics of rocking ships in a liquid with rigid vertical boundaries is quite limited.This fact is due to the change in the distribution of hydrodynamic pressures on the wet surface of the vessel, resulting in changes in quantitative and qualitative ratio of the total hydrodynamic forces acting on the vessel. Thus, the improvement of methods for calculating the rocking of ships in compressed waters (fairways) is an urgent task aimed at ensuring traffic safety. Decreasing the distance between the vessel and the vertical wall leads to a significant increase in the coefficients of attached masses and damping, changing the sign of the attached masses and shifting the maximum values in the high frequencies regardless of the depth of the fairway, and in turn values   of the coefficients of the connected masses, damping of perturbing forces and shifting of their maximum values in the low frequency range.The necessity of developing a three-dimensional numerical method for solving this problem is proved. The spatial potential problem of the ship's rocking in shallow water parallel to the vertical wall has been solved. A numerical calculation method has been developed.The analysis of the existing calculation methods for determining the hydrodynamic characteristics of the ship's wobble in the conditions of the fairway compressed by the vertical boundaries (in the channel, parallel to the berth) is carried out. The necessity of developing a three-dimensional numerical method for solving this problem is shown. The spatial potential problem of the ship's rocking in shallow water parallel to the vertical wall has been solved. A numerical calculation method has been developed.