Field measurement study on turbulence field by wind tower and Windcube Lidar in mountain valley

Due to the complexity of turbulence in mountain valley and lack of research focusing on such type of turbulence fields, which are critical for both buffeting response and vortex induced vibration (VIV) in slender structures, this paper aims to enhance the understanding of turbulence fields in mountain valley by investigating field measurement wind data obtained by a wind tower and a Windcube Lidar. Turbulence intensity, turbulent spectrum and vertical spatial coherence are obtained and analyzed according to the continuous measured data, which are significantly influenced by mountain terrain. Some of these characteristics are compared with current recommended specifications, standards and empirical formulas. The results indicate that turbulence intensity (e.g. probability density function (PDF) distribution, variation with mean wind speed and height) in mountain valley are very different from those recommended by the specifications and standards. It is identified that the Simiu and Panofsky spectral models could induce large discrepancies for mountain valley terrain in China Southwest, while the von Kármán spectral models can still well indicate such terrains. Furthermore, the vertical spatial coherences can be accurately expressed by some empirical coherence formulas for a mountain valley, but it is not feasible to adopt empirical coherence formulas with fixed parameters to represent the realistic coherence at different heights in a mountain valley. Meanwhile, the results have a general applicability for the determination of wind characteristics in the mountain areas of China Southwest.