Computational Modeling of Turbulent Flows Over Rough Surfaces
Computational Modeling of Turbulent Flows Over Rough Surfaces
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DOI：
10.1115/imece2003-41063
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发表时间：
2003
期刊：
影响因子：
--
通讯作者：
G. Chochua;W. Shyy
中科院分区：
文献类型：
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作者：
G. Chochua;W. Shyy
在自然界和工程实践中经常遇到粗糙表面上的湍流，并且通常难以分析。在这项研究中，结合建模和计算技术来研究这种流动在覆盖着大尺度粗糙度模式的表面上。通过对地表流场数据进行面积平均，验证了简化的经验工程模型。该方法可以基于经验相关性来解释流体物理。壁面法向时均速度分量产生的面积平均平均动量输运是近边界剪应力平衡的重要贡献项。这使得它的行为不同于光滑表面上的流动。比较了几种估计粗糙度系数的方法，发现质量-流量-亏缺法取得了较好的结果。以一壁覆盖有圆柱腔阵列而另一壁光滑的通道中的流动为例。基于k-e闭合和简化工程模型的扩展壁面函数可以应用于大规模的粗糙度模式。该方法可以显著降低所需的计算成本。另一方面，需要小域周期计算来产生特定表面几何形状的粗糙度长度。该模型可以建立粗糙度长度与表面几何形状之间的一般相关性，以帮助工程设计。ASME版权所有©2003
Turbulent flows over rough surfaces are often encountered in nature and engineering practices and are often difficult to analyze. In this study, combined modeling and computational techniques is involved to investigate such flows over a surface covered with a large-scale roughness pattern. A simplified empirical engineering model is validated by taking area average of the flow field data over the surface. The approach can interpret fluid physics based on the empirical correlation. The area-averaged mean momentum transport resulting from the wall-normal time-averaged velocity component is found to be a significant contributing term into the near-boundary shear stress balance. This makes its behavior different from the flow over a smooth surface. Comparing alternative approaches for estimating the roughness coefficients, it is found that the mass-flow-rate-deficit approach produces superior results. Flow in a channel with one wall covered with an array of cylindrical cavities and the other smooth is used as an example. The extended wall functions, based on the k-e closure and the simplified engineering model, can be applied for a large-scale roughness pattern. The approach can significantly reduce required computational cost. On the other hand, the small domain periodic computations are needed to produce roughness lengths for a particular surface geometry. This model can develop a general correlation relating the roughness lengths to a surface geometry to aid engineering design.Copyright © 2003 by ASME