ADV在波浪边界层流动特性研究中的应用

Application of ADV to turbulence characteristics near bed with wave layer

本文介绍新声学多普勒流速仪(Acoustic-Doppler Velocimeter)技术在波浪流动特性研究中的应用。通过波浪水槽试验,利用ADV测量椭圆余弦波作用下不同底床情况,垂线上各点的瞬时流速。将瞬时流速进行相位平均,计算了各点的紊动强度。试验结果显示:在平底床面,水平流速u沿水深变化曲线体现了椭圆余弦波流速的不对称性;分析紊动强度沿水深分布,两种床面上水平流速u的紊动强度明显大于另外两个方向,沙纹床面上由于受到分离涡的影响,紊动强度沿水深分布和平坦床面上的特性有较大不同。

The bottom boundary layer under cnoidal waves was studied by using Acoustic Doppler Velocimeter （ADV） technique in a laboratory flume. Time series of 3-D velocities were measured directly by ADV on the plane bed and rippled bed respectively. The velocity structure, turbulence intensity are studied by time series velocity data in the bottom layer. Several characteristics of flow structure are acquired, such as the asymmetry of horizontal velocity under cnoidal waves and the distribution of turbulence intensity on different type bed. By comparing the turbulence intensities along depth under different bed conditions, it is found that the turbulence intensities in horizontal velocity is evidently bigger than that in other two directions. With influence of votex motion, the distribution of turbulence intensities along depth over ripple bed is different from that over plane bed.