Study on dynamic characteristics of natural and mechanical wind in built environment using spectral analysis

What are the differences and similarities between natural and mechanical wind in built environment? This is an interesting question that has not been well answered yet. In the paper, spectral analysis is applied to study the dynamic characteristics of natural and mechanical wind in different conditions. The results show that in the frequency region sensitive to human sensation, the power spectrum characteristics of natural wind and mechanical wind have obvious differences as well as interesting connections. The power spectrum exponent (β$\beta$ value) of natural wind is between 1.1 and 2.0 in the human sensitive frequency region, while the value of mechanical wind is between 0 and 0.5 around the air supply outlet. With the diffusion of mechanical wind, β$\beta$ value will increase gradually and reach the value of the typical natural wind when the mean velocity is lower than 0.25 m/s. Finally, the influence of spectral characteristics on human sensation for airflow is discussed.