Wind spectrum and correlation characteristics relative to vehicles moving through cross wind field

In this study, based on Taylor׳s frozen turbulence hypothesis and isotropic turbulence model, the auto-correlation coefficient function of lateral wind fluctuation and cross-correlation coefficient functions of lateral and longitudinal wind fluctuations are derived from the Kaimal spectrum of longitudinal wind fluctuation. Based on the same hypothesis, this study also derived formulations for calculating the power spectra and correlation coefficient functions of wind turbulence relative to moving vehicles. The results can be applied for any vehicle moving direction, and for both longitudinal and lateral components of wind turbulence. The effects of speed ratio of moving vehicle to mean wind velocity and vehicle direction on the characteristics of wind turbulence relative to moving vehicles are investigated. In addition, a closed-form expression is also proposed to approximately represent the square-root coherence function of wind turbulence relative to moving vehicles. It provides useful insights for better understanding the characteristics of turbulent wind relative to moving vehicles, and also provides a theoretical foundation for solving the discontinuity of sudden change of wind fluctuations while the wind fluctuations are simulated using traditional fixed-point spectrum.