| This paper studies the visualization techniques of ship motion in waves. The results of scientific calculation are often abstract professional charts and data, Visualization of ship motion in waves enables ship architects to analyze the results of scientific calculation and thereby understand the ship motion property more intuitively.The random waves, non-linear damp and ship non-linear restore moment are taken into consideration and the ship rolling non-linear differential equation is established. The visualization techniques of ship motion in waves are described in OpenGL, a platform-independent graphics library. The ship model is built using ship offset that describes the shape of ships;The wave model is built using the Pierson-Moskowitz sea spectrum and Mitsuyasu angular distribution model. Non-linear damp and non-linear restore moment are taken into account and random disturbance moment is calculated according to narrowband sea spectrum, the differential equation is solved by using the 4th-order Runge-Kutta method, the animation of ship motion in waves is produced by the functions glRotate*() and glTranslate*() in the OpenGL library. This article studies the production of artificial random waves, numerical simulation of ship random non-linear motion and the visualization program for ship motion.The developed program simulated different cases of ship motion where the significant wave heights are 9.54m, 12.42m, 14.28m and 18.0m, respectively and implemented the visualization of ship motion in the random waves.The results indicate that it is feasible to visualize the ship motion in waves using the C++ programming language and OpenGL graphics hardware interface. One of the advantages of the program is portability by using the GLUT. The visualization program was developed on Windows and has been tested on Windows and Linux. Besides the fact that the source code is platform-independent, using C++ and OpenGL also has the advantage of being more flexible and more efficient than using CAD software. The program can read the offset from the data file and build the model. To simulate different ships, it's sufficient to store different offsets in the file. Meanwhile, the program developed in C++ executes much faster than the ones written in MATLAB and other CAD built-in scripting languages. |
