Three-dimensional Numerical Simulation Of Swimming Of Iomimetic Underwater Vehicle

The unmanned underwater vehicle(UUV) has become a focus for research and application all around the world. In order to solve the disadvantages of the traditional propulsion of UUV on efficiency and maneuverability performance, the propulsion of fishes and insects is used to help design new biomimetic propulsion used on UUV, which has become an important direction to develop UUV. The main work of the thesis is to use numerical methods to research the influence of the shape and the propulsion on the performance of UUV with the model of biomimetic UUV made by our group, which can help us to optimize the design of UUV.The thesis adopted Immersed Boundary Method(IBM) to simulate the interaction between UUV and the fluid, used Lattice Boltzmann Method(LBM) to simulate the flow of the fluid, and quaternion method was used to calculate the movement of UUV. Firstly, a program is compiled by Fortran based on CPU and the validation of the code is carried out by calculating the three-dimensional Poiseuille flow and the flow around a sphere. Secondly, as the time consumed by three-dimensional simulation is very long and the parallel performance of LBM is good, CUD A Fortran is used to implement the part of parallel calculation on GPU with PGI Fortran12.10, which can accelerate the calculation significantly.Then the influence of different parameters to the propulsion performance of double caudal fins of biomimetic UUV is studied. The result shows that to a certain extent the Reynolds number doesn’t affect the mechanism. When the swinging amplitude and beating frequency increase, the speed of swimming raises, but the power consumed also raises. To a certain extent, the high beating frequency can improve the speed, and there exists the best beating frequency. The flexible caudal fin is better than rigid caudal fin when the Reynolds isn’t very high. The propulsion performance of Semi-oval-shaped caudal fin is better than that of deeply forked tail fin when the caudal fin only swings in the simulation.The simulation of four wings of biomimetic UUV shows that the fast rotation can make the peak of thrust very high, and the drag is produced when the adjacent wings become farther, but the thrust is produced when the adjacent wings become closer. The speed of swimming is linear with the speed of swinging, but the power consumed is a quadratic function of the speed of swinging.