An analytical model for the fluctuating wind velocity spectra of a moving vehicle

An analytical model for both the longitudinal and lateral fluctuating wind velocity spectra of a moving train in the random wind field has been developed based on Cooper's theory (Cooper, 1984). The fluctuating wind velocity spectrum of a moving point can be derived through the weighted linear superposition of the longitudinal and lateral spectra of the stationary point with both frequency and amplitude scaling. The proposed analytical model has been validated systematically, and based on the Simiu spectrum (Simiu and Scanlan, 1996), parametric studies were conducted for the influence on the fluctuating spectra of a moving train by wind flow angle from 0 degrees, 30 degrees, 60 degrees, 90 degrees, to 150 degrees and varying speed ratios between vehicle and wind (mean wind velocity of 20 m/s) from 1 to 4. It is revealed that the fluctuating wind velocity spectrum experienced by a moving train exhibits a Doppler effect phenomena due to the train movement, especially in the longitudinal case. The proposed spectrum model can provide an efficient simulation scheme for the fluctuating wind velocity time series of the moving train with adequate accuracy and can provide a rigorous analytical scheme for the subsequent aerodynamic response analysis of the moving train within the random wind field.