Riblet Flow Model Based on an Extended FIK Identity
Riblet Flow Model Based on an Extended FIK Identity
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DOI：
10.1007/s10494-015-9624-2
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发表时间：
2015-06
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影响因子：
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通讯作者：
A. Bannier;E. Garnier;P. Sagaut
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文献类型：
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作者：
A. Bannier;E. Garnier;P. Sagaut
用大涡模拟方法对沟槽上的零压梯度湍流边界层进行了数值模拟。在整个受控区域，肋板相对于平板在相同Reτ下的减阻效果显著(从250%降至450%)。为了比较沟槽和参考光滑壁面上的流动，需要在两个表面之间进行适当的垂直移位。在本研究中，使用Fukagata、Iwamoto和Kasagi(FIK)在Phys中的身份来设置“垂直原点”。《流体》，2002年第14卷，第73页。这个恒等式提供了表面摩擦力的物理意义分解，已经扩展到复杂的墙表面，并构成了新的虚拟原点的推导基础。结果表明，通过简单地移动平均速度分布和湍流速度分布的两个轴，就可以考虑肋片和近壁湍流结构之间的复杂相互作用。适当的向上移动Δu+，通常用于减阻，直接取决于肋骨上的表面摩擦力和相同Reτ处的参考光滑板。
Large Eddy Simulations of zero-pressure-gradient turbulent boundary layers over riblets have been conducted. All along the controlled domain, riblets maintain a significant 11 % drag reduction with respect to the flat plate at the sameReτ(from 250 to 450). To compare the flows above riblets and a reference smooth wall, an appropriate vertical shift between the two surfaces is required. In the present study, the “vertical origin” is set using the identity of Fukagata, Iwamoto and Kasagi (FIK) inPhys. Fluids, vol. 14, 2002, L73. This identity, which provides a physically meaningful decomposition of the skin friction, has been extended to complex wall surfaces and constitutes the basis for the derivation of a new virtual origin. Using this FIK-based origin, it is shown that the complex interactions between the riblets and the near-wall turbulent structures can be taken into account by a simple shift of the two axes of the mean and turbulent velocity profiles. The appropriate upward shift Δu+, typical for drag reduction, is directly dependent on the skin friction on the riblets and on the reference smooth plate at the sameReτ.