Large eddy simulation study of 3D wind field in a complex mountainous area under different boundary conditions

Large eddy simulations generally are used to predict 3D wind field characteristics in complex mountainous areas. Certain simulation boundary conditions, such as the height and length of the computational domain or the characteristics of inflow turbulence, can significantly impact the quality of predictions. In this study, we examined these boundary conditions within the context of the mountainous terrain around a long-span cable-stayed bridge using a wind tunnel experiment. Various sizes of computational domains and turbulent incoming wind velocities were used in large eddy simulations. The results show that when the height of the computational domain is five times greater than the height of the terrain model, there is minimal influence from the top wall on the wind field characteristics in this complex mountainous area. Expanding the length of the wake region of the computational domain has negligible effects on the wind fields. Turbulence in the inlet boundary reduces the length of the wake region on a leeward hill with a low slope, but has less impact on the mean wind velocity of steep hills.