Structure of the Reynolds stress near the wall
Structure of the Reynolds stress near the wall
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DOI：
10.1017/s002211207200165x
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发表时间：
1972-09
影响因子：
3.7
通讯作者：
W. Willmarth;S. Lu
中科院分区：
文献类型：
--
作者：
W. Willmarth;S. Lu
本文报道了用热线探针对湍流边界层近壁流场的实验研究。产品紫外线的测量研究使用条件采样技术与大型数字计算机挑选出特殊事件（突发）时，发生大的贡献湍流能量和雷诺应力。用于确定何时对产品uv进行采样的标准是，子层边缘处的流向速度应达到一定值。用这个简单的标准，我们发现，60%的贡献$\overline{uv}$时，产生的子层速度低于平均值。这一结果在低雷诺数（Rθ = 4230）和高雷诺数（Rθ = 38000）时均成立。采用更严格的采样标准，即在两个并排点处的过滤子层速度应同时较低并逐渐降低，已确定个体对$\overline{uv}$的贡献高达62 $\overline{uv}$。使用截断的u和v信号之间的相关性的其他测量结果表明，雷诺应力和湍流能量的最大贡献发生时，u 0在一个激烈的爆发过程中，其余的贡献发生在一个不太激烈的恢复过程中。因此，湍流能量的产生和雷诺应力在壁附近的一点的贡献是相对较大的幅度，持续时间短，间歇性发生。在靠近墙的一点上，紫外线的不透明度因子的粗略测量值是0·55，因为对$\overline{uv}$的99%的贡献仅在总时间的55%内完成。
Experimental studies of the flow field near the wall in a turbulent boundary layer using hot-wire probes are reported. Measurements of the product uv are studied using the technique of conditional sampling with a large digital computer to single out special events (bursting) when large contributions to turbulent energy and Reynolds stress occur. The criterion used to determine when the product uv is sampled is that the streamwise velocity at the edge of the sublayer should have attained a certain value. With this simple criterion we find that 60% of the contribution to $\overline{uv}$ is produced when the sublayer velocity is lower than the mean. This result is true at both low, Rθ = 4230, and high, Rθ = 38 000, Reynolds numbers. With a more strict sampling criterion, that the filtered sublayer velocity at two side-by-side points should be simultaneously low and decreasing, individual contributions to $\overline{uv}$ as large as 62 $\overline{uv}$ have been identified. Additional measurements using correlations between truncated u and v signals reveal that the largest contributions to the Reynolds stress and turbulent energy occur when u 0 during an intense bursting process and the remainder of the contributions occur during a less intense recovery process. Thus, contributions to the turbulent energy production and Reynolds stress at a point near the wall are of relatively large magnitude, short duration and occur intermittently. A rough measure of the intermittency factor for uv at a point near the wall is 0·55 since 99% of the contribution to $\overline{uv}$ is made during only 55% of the total time.