Near-wall scaling for turbulent boundary layers with adverse pressure gradient
Near-wall scaling for turbulent boundary layers with adverse pressure gradient
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DOI：
10.1007/s00162-007-0055-0
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发表时间：
2008-05
影响因子：
3.4
通讯作者：
M. Manhart;Nikolaus Peller;C. Brun
中科院分区：
文献类型：
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作者：
M. Manhart;Nikolaus Peller;C. Brun
本文提出了一种新的扩展内标度方法，用于同时考虑壁面切应力和流向压力梯度影响的有壁流动的壁面层。这种换算避免了接近流动分离和再附着的经典壁面坐标的问题。基于所提出的扩展速度和长度尺度，导出了壁面附近粘性区域的通用无因次速度分布族，它取决于壁面距离和一个参数α，该参数α量化了动量平衡中流向压力梯度相对于壁面剪应力的重要性。在两个不同的流场，分离和再附着的湍流边界层和湍流流动的周期性安排的光滑轮廓的山丘的性能进行了研究。这两种流动都是高分辨率直接数值模拟（DNS）的结果。结果表明，粘性假设是有效的，约两个扩展的壁单元。如果轮廓由扩展的内部坐标缩放，则它们似乎以通用的方式表现。这就产生了这样的希望，即在所提出的扩展内坐标中可以找到速度分布的普遍行为，甚至超出了壁的扩展粘性定律的有效性。
A new extended inner scaling is proposed for the wall layer of wall-bounded flows under the influence of both wall shear stress and streamwise pressure gradient. This scaling avoids problems of the classical wall coordinates close to flow separation and reattachment. Based on the proposed extended velocity and length scales a universal nondimensional family of velocity profiles is derived for the viscous region in the vicinity of a wall that depend on wall distance and a parameter α quantifying the importance of the streamwise pressure gradient with respect to the wall shear stress in the momentum balance. The performance of the proposed extended scaling is investigated in two different flow fields, a separating and reattaching turbulent boundary layer and a turbulent flow over a periodic arrangement of smoothly contoured hills. Both flows are results of highly resolved direct numerical simulation (DNS). The results show that the viscous assumptions are valid up to about two extended wall units. If the profiles are scaled by the extended inner coordinates, they seem to behave in a universal way. This gives rise to the hope that a universal behavior of velocity profiles can be found in the proposed extended inner coordinates even beyond the validity of the extended viscous law of the wall.