Boundary condition setting method for processing irregular frequency in ship hydrodynamic calculation

Abstract

The invention discloses a boundary condition setting method for processing irregular frequency in ship hydrodynamic calculation, and relates to the field of ship hydrodynamic calculation. The method comprises the following steps: acquiring three unit correspondence relationships enabling the distance between every two subunits in a hull wet surface grid unit, a first-layer cover grid unit, a second-layer cover grid unit and a third-layer cover grid unit which are adjacent to a hull waterline to be minimumbased on the three-dimensional hydroelasticity equations of the hull and the three-dimensional boundary element method. expanding a boundary integral equation by adopting a method of scaling and assigning boundary conditions on the layered cover grid units, so so to further solve the radiation potential source intensity and diffraction potential source intensity of the hull wet surface grid units and the cover grid units in the waterline plane. The sudden change problem of boundary conditions of hull wet surface grids and capping grids is solved; the application of the irregular frequency elimination method in ship hydrodynamic force calculation is achieved.

Description

technical field [0001] The invention relates to the field of ship hydrodynamic calculations, in particular to a boundary condition setting method for dealing with irregular frequencies in ship hydrodynamic calculations. Background technique [0002] The hydrodynamic performance analysis of a ship is an important stage in the ship design process. In the three-dimensional potential flow theory of ships, the three-dimensional boundary element method combined with the complex Green's function method is usually used to obtain the relevant hydrodynamic parameters by calculating the distribution of source intensity on the wet surface of the hull. When using distributed sources to solve the hull surface velocity potential, it is necessary to satisfy the existence of the internal solution of the Laplace equation, but this internal solution does not always exist. When the frequency takes some special values, the internal solution does not exist, and these special frequencies are call...

AI Technical Summary

Problems solved by technology

But in the process of calculation, it is found that if all the boundary condition values ​​on the capped subunit at the water plane are set to zero, then the calculation can only eliminate the irregular frequency for the results within a certain frequency range, but for The calculation results of other higher frequency ranges have not been significantly improved. The setting method of subunit boundary conditions at the waterplane surface plays a very important role in eliminating irregular frequencies. Therefore, it is necessary to invent a waterplane surface with a cap Subunit boundary condition setting method to solve the irregular frequency problem in the process of ship hydrodynamic calculation more perfectly

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