Abstract

To improve our understanding on the aerodynamic wall shear fluctuation in particle-laden flow, we perform statistical and spectral analyses of aerodynamic wall shear fluctuation in sand-free and sand-laden flows in a turbulent boundary layer based on the results of a wind tunnel experiment. An increase in the skewness of the probability density function of aerodynamic wall shear fluctuation is found in the sand-laden flow. The turbulent intensity of aerodynamic wall shear stress increases rapidly with the sand mass flux. The decreased convective velocity indicates blocking effects of sand particles in the near-wall region. The power of aerodynamic wall shear fluctuation in the sand-laden flow increases at low frequencies corresponding to the duration of sand streamers. The results of a superstatistical analysis of skin friction velocity show that spatio-temporal fluctuation in the local energy dissipation rate is enhanced in the sand-laden flow. Finally, the local and spatio-drifting force acting on the stochastic system of wall shear fluctuation in sand-laden flow are different, providing a proof for the significant variation in flow condition caused by sand streamers near the wall

Graphic Abstract

中文翻译：

---

湍流边界层中含沙流中的气动壁面剪切波动

摘要

为了更好地理解含颗粒流中的气动壁面剪切波动，我们基于风洞实验的结果对湍流边界层中无砂和含沙流中的气动壁面剪切波动进行了统计和频谱分析。在载沙流中发现了气动壁剪切波动的概率密度函数的偏度的增加。气动壁剪应力的湍流强度随砂质通量的增加而迅速增加。对流速度的降低表明了近壁区域沙粒的阻塞作用。载沙流中的气动壁面剪切波动的能力在对应于流沙持续时间的低频下增加。皮肤摩擦速度的超统计分析结果表明，载沙流中局部能量耗散率的时空波动增加。最后，在含沙流中作用于壁面剪切波动的随机系统的局部力和时空漂移力是不同的，这为壁附近的流沙引起的流动条件的显着变化提供了证据。

图形摘要