Numerical Simulation And Characteristics Of Ship Wave Drag Increase Based On Fully Nonlinear Boundary Element Method

For the purpose of designing more excellent ships,it is necessary to accurately calculate the wave drag of ships sailing in sea conditions.However,the motion state of the ship in the actual sea condition and the wave drag increase involve more complex hydrodynamic theoretical research.Based on the boundary element method,this paper establishes a fully nonlinear mathematical model of the interaction between the three-dimensional hull and the wave in the time domain,develops the elastic mesh technology,fairing technology,the treatment technology of large deformation of the free surface and the decoupling method of the interaction between the floating body and the wave,and gives the calculation method for effectively simulating the motion of the ship in the wave under the fully nonlinear boundary conditions.This research mainly includes the following aspects :1)Research on the calculation method of ship wave drag under fully nonlinear conditions.Based on the three-dimensional potential flow theory,a fully nonlinear method based on the three-dimensional potential flow theory is established.This method separates the incident potential and the perturbation potential.The incident potential is given by the plane wave,and the perturbation potential is solved by Rankine source boundary element method considering both free surface nonlinearity and surface nonlinearity.The auxiliary function is introduced to decouple the motion and load in the rigid body motion equation,and the time domain update of the calculation model is realized by the fourth-order Runge-Kutta method.2)The full nonlinear boundary element method is used to study the static wave resistance and wave drag increase of Wigley III ship.The accuracy of the calculation method is verified by comparing with other test results.On this basis,the motion response and resistance time history curve of a amphibious ship are given.The ship’s wave drag increase under different speeds and wave parameters is calculated and analyzed,and the ship motion,wave characteristics,hydrodynamic pressure distribution and wave drag increase characteristics are given.