doi:
UDK: 531.391.1:532.5.011

DETERMINATION OF THE NONLINEAR COMPONENTS OF SECONDORDER FORCES DURING THE SHIP MOTIONS ON THE BASIS OF A THREEDIMENSIONAL POTENTIAL THEORY

Альбаев Д. А.
Article language: английский

Annotation

For a correct estimation of the seaworthiness and safety of ships or offshore structures, it is necessary to calculate with sufficient accuracy the non-linear forces acting on the object. In this paper, the hydrodynamic forces are corrected by taking into account second-order nonlinear components. This is ecessary to more accurately determine ship motion parameters (such as amplitudes, velocities, and accelerations). The evelopment of a numerical algorithm and programs is presented that allows determining the second-order potentials directly, taking into account nonlinear boundary conditions on a free and wetted surface for the cases of a water of infinite and limited depth. Grid convergence in the calculation of integrals over the free surface of water is given. Approbation of recast of calculation of double spatial derivatives of potentials with the help of theorems of Gauss and Stokes is carried out. Second-order nonlinear forces are determined in accordance with the small parameter method. Systematic calculations of non-linear forces acting on various vessels are carried out. The effect of changes in the relative depth and heading angle on them has been studied. An assessment of the influence of the components of nonlinear forces on the overall force impact on the object was carried out. It is shown that in the zone of action of the main and additional resonant modes, all considered categories of nonlinear forces have an equivalent effect. Keywords: ship motions, method of the integral equations, three-dimensional potential theory, the potential of the second order, Green’s function, nonlinear forces, shallow water

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