다중 구조물에 기인하는 해양파고 저감효과 수치해석

Abstract

Firstly, in order to solve the problem of fluid structure coupling，the flow around a circular cylinder is studied based on the lattice Boltzmann method. The two-dimensional D2Q9 model, Single-Relaxation-Time Lattice Boltzmann Method, Multi- Relaxation-Time Lattice Boltzmann Method, the Smagorinsky eddy viscosity model under the large eddy simulation and impedance boundary conditions are used to simulate the flow. The boundary condition of Bouzidi surface is adopted for the solid surface, which makes the solid surface meet the condition of no slip. The flow around a cylinder with Reynolds numbers of 500, 1000 and 3900 is calculated. Compared with the Single- Relaxation-Time Lattice Boltzmann method, the Multi-Relaxation-Time simulation has the advantage of less instability in all simulations. The simulation results of predicting the force coefficient and vortex shedding frequency of MRT-LBM with different constant Smagorinsky model show that this method can improve the numerical stability of LBM in high Reynolds number simulation. On this basis, the second-order Stokes nonlinear wave generated by the mass source method is simulated by establishing a numerical simulation water tank. The VOF method is extended to the free surface tracking in the LB model, and the variation equation of the distribution function in each direction is applied to the mass source wave generation. The upper and outlet of the numerical simulation wave tank are set as open boundary, while the bottom is set as solid boundary. . In order to effectively reduce the wave height of free surface, three different types of multi-structures are installed in the domain. The same gap is set between the structure and the structure to simulate the change of wave height. The numerical simulation results show that the numerical wave tank can effectively simulate the waves, avoid the secondary reflection of the waves in the calculation domain, have good wave elimination effect, and do not produce obvious reflected waves.