Velocity and Surface Shear Stress Distributions Behind a Rough-to-Smooth Surface Transition: A Simple New Model
Velocity and Surface Shear Stress Distributions Behind a Rough-to-Smooth Surface Transition: A Simple New Model
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粗糙到光滑表面转变背后的速度和表面剪切应力分布：一个简单的新模型
DOI：
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发表时间：
2009
期刊：
影响因子：
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通讯作者：
F. Porté
中科院分区：
文献类型：
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作者：
L. Chamorro;F. Porté
提出了一个简单的新模型来预测粗糙到光滑表面过渡的顺风风速和表面剪应力的分布。风速估计为两个限制对数分布之间的加权平均值：第一个对数法，这是恢复以上的内部边界层高度，对应于逆风速度分布;第二个对数法调整到顺风的空气动力学粗糙度和当地的表面剪应力，它是恢复在表面附近，在平衡子层。建议的加权因子的非线性形式等于ln（z/z 01）/ln（δi/z 01），其中z、δi和z 01分别是预测位置的海拔高度、该下风距离处的内部边界层高度和上风表面粗糙度。与其他简单的分析模型不同，新模型不依赖于内边界层内湍流剪应力的恒定或线性分布的假设。新模型的性能进行了测试与风洞测量，也与现场数据的布拉德利。与其他现有的分析模型相比，该模型显示出改进的预测表面剪应力和速度分布在不同位置的过渡顺风。
A simple new model is proposed to predict the distribution of wind velocity and surface shear stress downwind of a rough-to-smooth surface transition. The wind velocity is estimated as a weighted average between two limiting logarithmic profiles: the first log law, which is recovered above the internal boundary-layer height, corresponds to the upwind velocity profile; the second log law is adjusted to the downwind aerodynamic roughness and local surface shear stress, and it is recovered near the surface, in the equilibrium sublayer. The proposed non-linear form of the weighting factor is equal to ln(z/z01)/ln(δi/z01), where z, δi and z01 are the elevation of the prediction location, the internal boundary-layer height at that downwind distance, and the upwind surface roughness, respectively. Unlike other simple analytical models, the new model does not rely on the assumption of a constant or linear distribution for the turbulent shear stress within the internal boundary layer. The performance of the new model is tested with wind-tunnel measurements and also with the field data of Bradley. Compared with other existing analytical models, the proposed model shows improved predictions of both surface shear stress and velocity distributions at different positions downwind of the transition.