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標題: Study on the Effect of Wind Reduction by the Successive Windbreak Fence
作者: 張書豪
關鍵字: 防風柵
出版社: 水土保持學系

The purpose of this study is to investigate numerically the flows around successive windbreak fences so as to explore general flow behavior and the effect of wind reduction. Moreover, verifications and analyses of the results of wind tunnel experiments were performed to compare with the predictions and to guide the numerical parameters. By varying the number of the fence series and the distances among them, flow simulations were carried out on a systematic basis to obtain general design guidelines of the successive windbreak fence. The results were then analyzed to compare the flow characteristics and wind reduction area.
In the numerical computations, a weakly compressible method, based on a finite volume approach, were adopted. To reflect the turbulence nature of the flow, a large eddy simulation with a subgrid-scale turbulence model were applied.
The conclusions are drawn as follows:
1. Based on the sheltered area as defined, the windbreak fence with a porosity of 30% leads to a better wind reduction effect than that of a solid wall.
2. In the case of two-series windbreak fences, a better wind reduction effect between the fences is obtained when the distance between the fences is within 16 to 18 times of the fence height. Moreover, in the studied cases, the best effect in the area behind the second fence is obtained when the fence distance is set as 22 times of the fence height.
3. For three-series windbreak fences, the best combinations is that the distances among the fences are set respectively as 16 and 12 times of the fence height. As the area behind the third fence is of concern, the best result is obtained when the gaps of the fences are set as a short-long type. On the other hand, among the studied cases, the worst wind reduction effect appears when the gap distances are the same (14H or 16H, H being the fence height).
Appears in Collections:水土保持學系

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