THE LATERAL DISTRIBUTION OF DEPTH-AVERAGED VELOCITY IN CONSECUTIVE BENDS WITH POOL-POINT BAR

This paper proposes an analytical approach to modeling the lateral distribution of depth-averaged streamwise velocity for flow in consecutive bends with pool-point bar based on the depth-integrated Navier-Stokes equations. The additional secondary flow and yet fully developed flow are assumed to be a linear function of the lateral distance. Then, the model for calculating the average vertical velocity distribution along the cross section of the pool region and the point bar regions is presented, and it is applied to consecutive bends with pool-point bar. By calibrating the calculated parameters from the measured data, the model can calculate the average longitudinal velocity distribution of vertical cross-section under different outlet water depth. The modeled results agree well with experimental data. The value rules of the parameters have analyzed for different water depth and along the cross-sections. Sensitivity analysis is performed on the parameters which showed that the region division of the coefficient of the first degree term in the linear hypothesis has great influence on the size and position of the peak flow velocity. The region division of the constant term value is according to the traverse gradient. The region edge between the flat bed and the sloping bed of the constant term has a significant influence on the results. According to the sensitivity of parameters, the mean value of parameters along the flume is presented as a reference value. The transverse distribution of the secondary flow term and the additional stress term in the depth-integrated Navier--Stokes equations along the experimental channel is discussed to further understand the applicability of the linear hypothesis. The results show that the linear hypothesis is suitable for the curve path in the flume. The research results are helpful to understand the longitudinal velocity distribution characteristics and the formation mechanism of the consecutive bends with pool-point bar.