Multiscale simulation of wind field on a long-span bridge site in mountainous area

A multiscale coupling strategy is proposed in the present study to numerically simulate the wind field at bridge sites in mountainous areas. This paper mainly focuses on resolving the difficulty of configuring reasonable inlet boundary conditions to achieve the required wind field. Firstly, the inlet boundary values of the mean wind velocity in the mountainous area were provided by the Weather Research and Forecasting (WRF) mesoscale model. Then, the local wind environmental flows over the mountainous area were computed by the large eddy simulation (LES) in such a way that the Block Polynomial Interpolation (BPI) method was employed to interpolate the data from WRF to the grids at the inlet boundary of the LES computation domain. This BPI method provided a better solution to the inlet boundary problems caused by the "artificial cliff". The inflow turbulence generating method was used for the input of the fluctuating wind speed at the inlet boundary, where the fluctuating wind field that satisfies the characteristics of the wind field in the mountainous area was simulated according to the data measured at the bridge site station by using the Weighted Amplitude Wave Superposition (WAWS) method. Finally, the proposed methodology was applied to the Lishui Bridge in China as a case study. The numerical predictions were found in good agreement with the monitored data, assuring the good capabilities of the proposed methodology and its potential uses in practical engineering. Meanwhile, the wind field from different wind directions was systematically studied and the characteristics for the detailed wind field distribution were analyzed. The presented methodology can be served as a reference to the refined simulation for the fluctuating wind field in mountainous areas.