G-N wave model-based forecast method for large-amplitude motion of ship in severe sea condition

Abstract

The invention discloses a G-N wave model-based forecast method for a large-amplitude motion of a ship in a severe sea condition, and belongs to the technical field of ship motion forecast. Through nonlinear simulation of the motion of the ship in waves, a nonlinear effect of an incident wave force and a hydrostatic restoring force of a ship body is considered, and an incident wave pressure on thewet surface of the ship body is calculated. A fluid pressure is solved based on a G-N wave theory, so that the incident wave force and a hydrostatic pressure are obtained; a radiation force and a diffraction force are solved by adopting an impulse response function method, wherein the wave surface of the diffraction force is obtained by a G-N wave model; and consistency correction can be performedin calculation. The large-amplitude motion of the ship is forecast by adopting a weak nonlinear motion equation based on coupling of three freedom degrees including heaving, pitching and rolling; RAOis calculated for analyzing motion characteristics of the ship; a simulated motion response time history significant valve, a motion extremum value and oscillation statistics are analyzed by utilizing a wave-by-wave analysis theory; and the motion of the ship body can be forecast more accurately.

Description

technical field [0001] The invention belongs to the technical field of ship motion prediction, and in particular relates to a method for forecasting large-scale motion of ships in bad sea conditions based on a G-N wave model. Background technique [0002] Using the potential flow method based on the nonlinear effect of the object surface to study the nonlinear motion of the ship in the wind and waves can grasp the main contribution of the large-scale motion of the ship from the nonlinear hydrodynamic load of the incident wave force and the static water restoring force, which can be more accurate The hydrodynamic nonlinear effect reflecting the large-scale motion of the ship is especially suitable for the nonlinear analysis of the large-scale motion of the ship from the perspective of calculation accuracy and efficiency. In the process of numerical simulation of ship nonlinear motion, the accuracy of numerical simulation of waves greatly affects the accuracy of numerical simu...

AI Technical Summary

Problems solved by technology

However, in severe sea conditions, the linear wave theory has certain limitations and cannot accurately simulate the motion of the ship.

[0005] Due to the strong nonlinear hydrodynamic effects and the strong dispersion of wave propagation in severe sea conditions, the current stochastic wave model based on linear wave superposition cannot reasonably describe the natural characteristics of such extreme waves. Therefore, a new tomographic Water wave theory G-N wave model is applied

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