Modeling and simulation of fluctuating wind speeds using evolutionary phasespectrum

According to the characteristics of vortexes with different frequencies in atmospheric turbulence, a rational hypothesis is proposed in the present paper that the time history of fluctuating wind speeds can be viewed as the integration of a series of harmonic waves with the same initial zero-phase. A univariate model of phase spectrum is then developed which relies upon a single argument associated with the concept of starting-time of phase evolution. The identification procedure of starting-time of phase evolution is detailed and its probabilistic structure is investigated through the estimation of the measured data of wind speeds. The univariate phase spectrum model is proved to be valid, bypassing the need of the classical spectral representation techniques in modeling the phase spectrum where hundreds of variables are required. In conjunction with the Fourier amplitude spectrum, a new simulation scheme, based on the stochastic Fourier functions, for fluctuating wind speeds is developed. Numerical and experimental investigations indicate that the proposed scheme operates the accurate simulation of fluctuating wind speeds efficiently that matches well with the measured data of wind fields by revealing the essential relationship among the individual harmonic waves. The univariate phase spectrum model exhibits the potential application for the accurate analysis and reliability evaluation of random wind-induced responses of engineering structures.