A semiempirical model for horizontal distribution of surface wind speed leeward windbreaks
A semiempirical model for horizontal distribution of surface wind speed leeward windbreaks
复制标题
背风防风林表面风速水平分布的半经验模型
DOI：
10.1007/s10457-019-00417-0
复制
发表时间：
2019
影响因子：
2.2
通讯作者：
Xiaofeng Xu
中科院分区：
文献类型：
--
作者：
F. Yuan;Jiabing Wu;An;D. Guan;Yu;Kavita Irene Rajah;Xiaofeng Xu
利用防风林是一种全球通行的农业生产管理做法，通过减少风致破坏恢复退化的生态系统。研究防风林如何影响背风面风速对于量化防风林的效率至关重要。结合风洞试验和现有文献资料，建立了模拟背风面风速水平分布的半经验模型。该模型模拟了水平背风面风速分布的防风林，同时考虑了防风林气动孔隙率、表面粗糙度、Richardson数和风入射角4个关键影响因素。它还包括一个简单的定量方法，确定防风林气动孔隙度从光学孔隙度。模型结果与已发表的数据比较表明，该模型在不同的风速分布，不同的防风结构和湍流条件下是鲁棒的。模拟结果表明，水平风速分布与防风林开孔率密切相关。风速随风入射角的增大而减小。当水平距离在2 ~ 20倍防风林高度范围内时，风速随Richardson数的增大而明显减小，随地表粗糙度的减小而略有减小。此外，风速入射角的增大增强了防风林孔隙度对风速的减弱作用，而Richardson数的减小则扩大了相对风速随地表粗糙度增大而减小的区间。该模型提供了一种简单实用的方法，以更好地评估防风林的影响，这可以被纳入农业政策制定的决定，以减少风的有害影响。
The utilization of windbreaks is a globally prevailing management practice for agricultural production and restoration of degraded ecosystems by reducing wind-induced destruction. Examining how windbreaks affect leeward surface wind speed is critically important to quantify the efficiency of windbreaks. A semiempirical model for simulating horizontal distribution of wind speed leeward windbreaks was developed, combining wind tunnel experiments with prevailing literature. The model simulated the horizontal leeward wind speed distribution windbreaks with acceleration and deceleration terms; simultaneously considering four key impact factors (windbreak aerodynamic porosity, surface roughness, Richardson number and wind incident angle). It also comprises of a simple quantitative method for determining windbreak aerodynamic porosity from optical porosity. Model results compared with published data illustrate that the model is robust in various wind speed distributions under different windbreak structures and turbulence conditions. The simulation results indicate horizontal wind speed distribution is definitely dependent upon windbreak porosity. Wind speeds decline with increasing wind incident angle. Wind speeds decrease obviously with increasing Richardson number while decrease slightly with decreasing surface roughness, when the horizontal distance is between two and twenty times the windbreak height. Moreover, the escalating wind incident angle strengthens the weakening effects of windbreak porosity on wind speed, while reducing Richardson numbers expand the decreasing intervals of relative wind speed with increasing surface roughness. The model provides a simple and practical method to better assess the impacts of windbreaks, which can be incorporated in agricultural policy-making decisions to reduce the detrimental impacts of wind.