Double-averaged velocity profiles over fixed dune shapes
Double-averaged velocity profiles over fixed dune shapes
复制标题
固定沙丘形状的双平均速度剖面
DOI：
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发表时间：
2008
期刊：
影响因子：
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通讯作者：
S. Coleman
中科院分区：
文献类型：
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作者：
S. Mclean;V. Nikora;S. Coleman
时间平均速度的空间平均分布，使用积分薄水平板（笛卡尔双平均），用于表征流动超过固定沙丘形状。为了进行比较，还研究了Smith和姆克林（1977）的空间平均法，该方法沿距离当地河床高程恒定距离的沿着进行平均。速度切变的倒数的笛卡尔双平均剖面在波峰高程以下几乎是恒定的，但在波峰高程以上迅速增加。这导致速度剖面随着距波峰下方床的距离线性增加。在波峰以上，可以认为速度是按几何规律增加的，但也可以认为是幂律分布。空间平均涡粘性剖面通过平均雷诺应力乘以反剪切来计算。由此产生的轮廓比均匀流对应物更复杂。
Spatially averaged profiles of time averaged velocity, using integrals over thin horizontal slabs (Cartesian double average), are employed in characterizing the flow over fixed dune shapes. For comparison the spatial averaging method of Smith and McLean (1977) that averages along lines at constant distance from the local bed elevation is also investigated. The Cartesian double averaged profiles of the inverse of the velocity shear are nearly constant below the crest elevation, but increase rapidly above the crest level. This results in velocity profiles that increase linearly with distance from the bed below the crest. Above the crest it can be argued that the velocity increases logarithmically, but a power law profile can also be argued. Spatially averaged eddy viscosity profiles are calculated by multiplying the average Reynolds stress by the inverse shear. The resulting profile is more complex than the uniform flow counterpart.