THE DETERMINATION OF NONLINEAR FORCES OF THE SECOND ORDER DURING THE SHIP'S VERTICAL MOTIONS, BASED ON THE THREE-DIMENSIONAL THEORY

The article deals with the definition of nonlinear forces arising in the vertical motions of the ship on the basis of three-dimensional potential theory.To determine them, it is necessary to calculate the potential of the second order of smallness. The presented solution in national practice is new. The solution of the problem is carried out on the basis of small parameter methods and integral equations taking into account nonlinear boundary conditions on the wetted surface of the ship and the free surface of the liuid. Nonlinear vertical forces are determined in the work using various Green functions: for an infinitely deep fluid and a fluid of limited depth when H -> infinity. The results obtained are completely consistent with each other. The results of calculations of the components of nonlinear vertical forces for four different ships are presented. The calculations are presented in comparison with the calculations according to the two-dimensional theory, also performed for the case of an infinitely deep liquid and liquid of limited depth for large values of the ratio of depth to sediment H / T. Good agreement between the results is shown