# Wind Field Characteristics of Complex Terrain Based on Experimental and Numerical Investigation
## 6 Conclusions  
By means of numerical simulation and a wind tunnel test, a terrain model of an island within 13 km of 1:1300 is established, and the wind characteristics of the terrain are discussed. Once the control wind directions are determined by numerical simulation, the wind tunnel test is conducted in conjunction with the most common wind direction in practice. A series of studies makes it possible to draw the following conclusions:  
(1) The wind profile coefficient is discrete, which is quite different from the recommended value of 0.12. Due to the influence of topography, the wind profile coefficients of different topographic characteristic areas under the same flow are different, and even the wind profile coefficients of the same measuring point under different flows are also different. For the hillside area, the wind speed on the windward slope is larger and the wind speed on the leeward slope is smaller, which is related to the elevation. The wind speed in flat areas is related to the incoming wind direction. When the incoming flow is not blocked, the wind speed is larger, and when blocked, the wind speed decreases. The wind speed in the valley is often low, and as the incoming current enters along the valley, it will have some acceleration effect in the low-level area. (2) The wind attack angles of each measuring point under different inflows are mainly in the range of \(-10^{\circ}\)-\(10^{\circ}\). As the height increases, the value of the wind attack angle tends to decrease progressively, but it is much higher than in plain areas. The wind attack angles of the windward slope are positive and those of the leeward slope are negative, both of which are often large. In addition, the wind attack angles in the valley are relatively large, and most of the wind attack angles in flat areas are small. It can be seen that the positive and negative wind attack angles are controlled by the incoming wind direction and the size is closely related to the local terrain. (3) The turbulence intensity on the windward slope is related to the elevation, which is larger near the foot of the mountain and smaller near the top of the mountain. The turbulence intensity of the leeward slope is larger near the ground. The turbulence intensity in the valley is generally large, and the turbulence intensity in the flat area is controlled by the surrounding terrain. No matter where the measuring point is located, it is different from the specification value of 0.12. In general, it should be significantly greater than 0.12. The fluctuating wind speed power spectrum on the island is more consistent with the von Karman spectrum, which is quite different from the Kaimal spectrum. As the complexity of the local terrain increases, the energy distribution shifts to high frequency. In addition, the bandwidth on the hillside is always at a great value, whereas the valley is the opposite, and the bandwidth of flat areas is greatly affected by the direction of the inflow. (4) This study shows that the wind characteristics of different areas on the island terrain are quite different, and they are more complex due to the variability in wind direction. The installation position of the turbine needs to consider the combined effects of wind speed, wind attack angle and pulsation characteristics. In addition, it is feasible to study the wind characteristics through the combination of a wind tunnel test and numerical simulation. Conceptualization, Y.Z. and Q.L. ; methodology, X.H. and Y.Z. ; software, P.Y. ; validation, Y.Z., P.Y. and X.H. ; formal analysis, P.Y. ; investigation, Y.Z. ; resources, Y.Z. ; data curation, P.Y. ; writing--original draft preparation, P.Y. ; writing--review and editing, Q.L. ; visualization, P.Y. and Z.W. ; supervision, X.H. ; project administration, Q.L. ; funding acquisition, Z.W. All authors have read and agreed to the published version of the manuscript.