Enhanced injection method for synthetically generated turbulence within the flow domain of eddy-resolving simulations
Enhanced injection method for synthetically generated turbulence within the flow domain of eddy-resolving simulations
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涡流解析模拟流域内综合生成湍流的增强注入方法
DOI：
10.1016/j.camwa.2017.12.012
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发表时间：
2018
期刊：
影响因子：
--
通讯作者：
Breuer
中科院分区：
文献类型：
--
作者：
De Nayer;Schmidt;Breuer
涡流分辨湍流模拟的质量在很大程度上取决于适当的入流条件。在大多数情况下，它们必须与时间相关，并满足一阶矩（平均速度）和二阶矩（雷诺应力）以及适当长度尺度的某些条件。为了模拟物理上真实的来流，叠加在平均速度场上的综合生成的湍流速度波动是一种有价值的解决方案。然而，入口附近网格的分辨率必须足够精细，以避免湍流强度的过度衰减。为了避免这个问题，合成生成的流入数据的注入不是在入口本身，而是在感兴趣区域附近的流域内，其中网格通常要精细得多，是一个优雅的漏洞。在本研究中，两种不同的注入技术的基础上的源项配方进行了分析和评价。除了这些技术之外，注入的数据还通过定义影响区域的高斯分布进行加权。在最近的工作中，与施密特和布鲁尔（2017）的初始版本相比，影响区域的定义得到了增强，扩展了应用范围。与网格单元尺寸相比，影响区域相当小的情况现在得到解决，这通常与工业应用相关。绕流壁装半球被选为测试情况。在Re= 50，000时，海崖体暴露于厚湍流边界层。在本调查中的湍流速度波动的产生依赖于数字滤波器的概念，但评价的注入技术并不限于此流入发生器。在半球上游约一个直径处注入合成湍流速度波动。壁面分辨大涡模拟进行了两个网格分辨率和相应的结果进行了分析，并与参考测量Wood等。（2016年）。最后，一种注入技术被发现是明显优于其他上级，因为它保证了正确的水平的速度波动和再现的自相关。
The quality of eddy-resolving turbulence simulations strongly depends on appropriate inflow conditions. In most cases they have to be time-dependent and satisfy certain conditions for the first (mean velocities) and second-order moments (Reynolds stresses) as well as concerning suitable length scales. To mimic a physically realistic incoming flow, synthetically generated turbulent velocity fluctuations superimposed on the mean velocity field are a valuable solution. However, the resolution of the grid near the inlet has to be sufficiently fine to avoid excessive damping of the turbulence intensity. In order to circumvent this problem, the injection of synthetically generated inflow data not at the inlet itself but inside the flow domain near the area of interest, where the grid is typically much finer, is an elegant loophole. In the present study two different injection techniques based on a source-term formulation are analyzed and evaluated. In addition to these techniques the injected data are weighted by a Gaussian distribution defining the influence area. In the recent work the definition of the influence area is enhanced compared to the initial version of Schmidt and Breuer (2017) extending the application range. The case of a rather small influence area in comparison with the grid cell size is now tackled which is often relevant for industrial applications. The flow past a wall-mounted hemisphere is chosen as test case. The bluff body is exposed to a thick turbulent boundary layer at Re= 50,000. The generation of the turbulent velocity fluctuations in the present investigation relies on the digital filter concept, but the injection techniques evaluated are not restricted to this inflow generator. The synthetic turbulent velocity fluctuations are injected about one diameter upstream of the hemisphere. Wall-resolved large-eddy simulations are carried out for two grid resolutions and the corresponding results are analyzed and compared with the reference measurements by Wood et al.(2016). Finally, one injection technique is found to be clearly superior to the other, since it guarantees the correct level of the velocity fluctuations and the reproduction of the autocorrelations.
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DOI：
--
发表时间：
2018
期刊：
影响因子：
--
作者：
S. Schmidt;M. Breuer
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作者：
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DOI：
10.1063/1.857955
发表时间：
1991-07-01
期刊：
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影响因子：
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作者：
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DOI：
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发表时间：
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期刊：
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