Wind resource assessment in complex terrain using the spatio-temporal downscaling coupling of WRF-steady RANS simulation

The meso -micro coupled numerical simulation method has been gradually adopted for high-resolution wind resource assessment. However, the accuracy of downscaling from mesoscale to microscale in complex mountainous terrain remains a huge challenge. In this study, a numerical simulation method of wind field based on meso-micro coupling suitable for wind resource assessment in complex terrain was proposed to improve the accuracy of downscaling. For this method, the optimal Planetary Boundary Layer (PBL) scheme is determined based on Weather Research and Forecasting (WRF) simulations for complex mountainous wind fields. And the Inverse Distance Weighted Interpolation (IDW) and time-averaging strategy were used in the proposed method to drive the coupled unsteady WRF - steady Reynolds Averaged Navier Stokes (RANS) simulations. The results showed that the Mellor Yamada Nakanishi Niino (MYNN) scheme demonstrated better performance than other PBL schemes. Furthermore, Finer time segmentation could improve simulation results, especially for the case of fluctuating wind speed, and a 50% overlap time length gave the favorable agreement with the measured data. In summary, the framework of WRF-steady RANS had excellent applicability in complex mountainous regions. The proposed spatio-temporal downscaling method is helpful to improve the accuracy and efficiency of mountain wind field simulation, which is of great engineering significance for wind resource assessment.