Abstract The paper presents an experimental study on the characterization of the effect of surface-wave of different frequencies on spatially-averaged turbulent statistics over a rough bed. The model roughness comprised of periodically positioned, transverse square ribs that extended across the whole width of the channel. The three-dimensional turbulent velocity fluctuations were mapped by an acoustic Doppler velocimeter (ADV) in the flow domain at high resolution. These data were analyzed to examine time-space averaged turbulence parameters of the double averaged Navier Stokes equations and momentum transfer under the influence of the rough boundary. Further, Shannon entropy at different vertical position were also evaluated to develop insight into the energy transfer mechanism. Results show a reduction in the apparent roughness height and an increase of the intensity of turbulence under surface wave influence. Furthermore, the superposition of waves led to the increase in turbulence production and showed maximum values at the roughness layer as compared to buffer layer in current-only flow over plane bed.

中文翻译：

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稳定流上存在单向波时肋状表面上的空间平均湍流特性

摘要 本文介绍了不同频率的表面波对粗糙层上空间平均湍流统计的影响表征的实验研究。模型粗糙度由在整个通道宽度上延伸的周期性定位的横向方形肋条组成。三维湍流速度波动由声学多普勒测速仪 (ADV) 在流域中以高分辨率绘制。分析这些数据以检查在粗糙边界影响下的双平均 Navier Stokes 方程和动量传递的时空平均湍流参数。此外，还评估了不同垂直位置的香农熵，以深入了解能量转移机制。结果表明在表面波影响下，表观粗糙度高度降低，湍流强度增加。此外，波的叠加导致湍流产生的增加，并且与仅流过平面床的缓冲层相比，粗糙度层显示出最大值。