Estimation of the Drag of a Hemisphere on a Flat Plate
Estimation of the Drag of a Hemisphere on a Flat Plate
复制标题
平板上半球阻力的估计
DOI：
10.1299/kikaib.73.1167
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发表时间：
2007
期刊：
影响因子：
--
通讯作者：
Qin
中科院分区：
文献类型：
--
作者：
Y. Miyake;T. Fujii;Qin
作者提出了一个不规则锯齿状粗糙表面的模型，其中高峰被拾取并由与相应峰具有相等体积的半球表示。在实际应用中，用平板上的平面剪应力代替半球的阻力。该简化模型表面用于模拟原始粗糙表面上的流动。该模型需要一个半球在平板上的阻力。本文通过数值模拟，研究了一种简单、准确且能与模型的紧凑性相平衡的独特的阻力公式。在用RANS对两个平板上具有周期性排列半球的通道流进行模拟的基础上，推导出了平板上半球的计算公式。证实所得公式与不同环境条件下不同尺寸半球所实现的公式比较合理，在粗糙壁面通道流动中，尽管阻力有很大的分散。该形式也适用于具有周期性半球在壁上的管道流动，并被发现再现测量摩擦，令人满意。虽然所提出的思想还需要进一步的仔细检验和细节上的改进，但已经建立了一个有希望的步骤，使所提出的模型在实际应用中成为一个有用的方法。
A model for an irregularly indented rough surface has been proposed by the authors in which tall peaks are picked up and represented by hemispheres having equal volume to corresponding peak. In practical application, drag of a hemisphere is substituted by plane shear stress on a flat plate. This simplified model surface is used to simulate flow over the original rough surface. The model requires drag of a hemisphere on a flat plate. In this work, unique drag formula which is simple and acceptably accurate in balance with the compactness of the model, is investigated by numerical simulations. The formula for a hemisphere on a flat plate is deduced on the basis of simulations by RANS, of channel flows having periodically arranged hemispheres on both plates. Obtained formula is confirmed to compare reasonably to those realized by hemispheres of different size in different ambient situation, in a rough wall channel flow, though drag largely scatters. The form is applied also to pipe flows having periodic hemispheres on the wall and is found to reproduce measured friction, satisfactorily. Although the proposed idea must be examined farther carfully and should be improved in details, promising step has been set up to make proposed model a useful method in practical application.