Efficient simulation of fully nonstationary wind velocity field by an enhanced numerical truncation method

Abstract

The spectral representation method (SRM) is widely utilized to simulate the fully nonstationary wind velocity field with time-varying coherence. The simulation samples are generated by double summation of harmonic functions. Despite the fast Fourier transform (FFT) technique has been employed to accelerate the summation in the frequency dimension, the computational efficiency is still constrained by the number of simulation points and samples due to the time-consuming summation operation in the spatial dimension. In this study, a numerical truncation method is presented to further quicken the SRM-based simulation of a fully nonstationary wind velocity field. The fundamental idea is that the harmonic functions with tiny amplitude are inconsequential and can be omitted. A novel diagonal decoupling approach is first developed to rearrange the double summation. Further, the frequency truncation scheme is established to simplify the summation in the spatial dimension. Meanwhile, the FFT operations to calculate the summation in the frequency dimension are also considerably reduced. Finally, the superior performance of the proposed method on precision and efficiency is demonstrated by numerical examples.