The Simulation Of Deep-sea Fluid In Underwater Vehicle Navigation System

We simulate the interaction of submersibles with deep-sea fluids,which take the underwater vehicle simulation system as the background and based on the stability and convergence of the fluid equation.We analyze the stability and convergence of fluid modeling,and perform physical modeling and visual simulation of deep-sea hydrothermal fluids.Meanwhile,we choose the best iterative method in the multigrid to satisfy the Poisson equation,simulate the interaction between fluid and solid,and apply it to the actual simulation system.The main contents of the dissertation are as follows:We analyze the stability and convergence of fluid m odeling.We use the difference equation to discretize the fluid equation with Fourier analysis to determine the stability of the difference.Then,we use an iterative method to solve the Poisson equation,and perform a Fourier analysis on the reason why the multigrid method can improve the convergence speed of the Poisson equation.Finally,we summarize the stability conditions and advantages and disadvantages of the explicit and implicit schemes of the difference equation.We physically simulate and visualize the deep-sea hydrothermal fluid in the submarine navi-gation simulation system.First,we simulate it physically with temperature,density,vorticity and velocity as the background,construct the appropriate dynamic equations,discuss the cause of the vorticity generated by the hydrothermal rise.Then,we use the implicit semi-Lagrangian method for the temperature and density fields to make the equation unconditionally s table.Meanwhile,we choose the Vortex-In-Cell method that combines the grid and the particles,which saves the vorticity in the form of particles in vortex particles.Finally,we perform physical modeling and visual simulation of deep-sea hydrothermal fluids based on these principles.We analyze different structures and cycle patterns of multigrid methods and choose the best iterative method to satisfy the Poisson equation in fluid s imulation.We analyze the principle of the two-grid and discuss how to effectively eliminate low frequency components to improve the convergence speed.According to the principle and process of the two-grid,we nest the two-grid to obtain the V-cycle structure,and obtain the W-cycle and FMG cycle.We analyze structures of algebraic multigrids and geometric multigrids and compare the principles of their limits and extension operators.We use red-black Gauss-Seidel iteration to perform parallel calculations on the GPU,and make full use of shared memory for calculations at the coarsest layer of the multigrid.Finally,we compare the convergence of algebraic and geometric multigrids in the V and FMG cycles and put them in the fluid simulation.We apply the simulation between solid and fluid in the actual simulation system in order to perform the coupling between submersible and deep-sea fluid.We deal with the boundary from t-wo aspects of velocity and vorticity,and satisfy the boundary conditions of no-slip and no-through on the boundary surface.To ensure real-time simulation,we simplify irregular solids into simple geometries.Finally,we simulate the effect between fluid and geometry in experiments and com-pare the time consuming.At the same time,we verify the no-through and no-slip boundary condi-tions through propeller wake experiments,and simulate the interaction between the hydrothermal fluid and the vortex wake generated by the propeller rotation.