Flow Structure in Partially Vegetated Rectangular Channels

This article discusses the transverse distributions of the depth averaged velocity and the Reynolds stress in a steady uniform flow in partially vegetated rectangular channels. The momentum equation is expressed in dimensionless form and solved to obtain the depth averaged velocity. The analytical solution of the velocity in dimensionless form shows that the depth-averaged velocity is determined by gravity and its distribution is mainly determined by the frictions due to water or vegetations. The analytical solution of the Reynolds stress is also obtained. A relationship between the second flow and the inertia is established and it is assumed that the former is proportional to the square of the depth averaged velocity. The Acoustic Doppler Velocimeter (Micro ADV) was used to measure the steady uniform flow with emergent artificial rigid vegetation. Comparisons between the measured data and the computed results show that our method does well in predicting the transverse distributions of the stream-wise velocity and the Reynolds stress in rectangular channels with partially vegetations.