漂浮植被的阻流特性研究

Study on resistance characteristics of suspended vegetation

为了定量研究漂浮植被的阻流特性,采用电子应力计对漂浮植被的拖曳力进行测量,基于边界层理论对其受到的拖曳力进行计算分析,并将实测的植被-水体交界面处切应力与基于边界层理论计算得到的拖曳力值进行了对比分析.研究结果表明:在充分发展的湍流边界层中,将边界层理论用于分析漂浮植被拖曳力是可行的;漂浮植被摩擦阻力的大小与速度的平方成正比,而压强阻力的大小与流速的平方成反比;植被拖曳力系数由植被区长度雷诺数和植被区高度雷诺数共同决定.

Electronic stress meter was adopted to measure the suspended vegetation drag force, and the boundary layer theory was used to calculate the drag force caused by suspended canopy. Then, the measured and predicted shear stresses on the vegetation-water interface were compared and analyzed. The results indicate that it is feasible to use boundary layer theory to calculate the drag force of float- ing vegetation, especially for fully developed turbulent boundary layer; the frictional resistance increa- ses with the square of depth-averaged streamwise velocity, but the pressure resistance decreases with the square of depth-averaged streamwise velocity; the drag coefficient varies with both the length Reynolds number （based on the length of suspended vegetation patch） and the height Reynolds num- ber （based on the vertical height of the patch）.