Experimental and Numerical Study on Velocity Fields Profile in consecutive Open Channel Bends

The flow pattern changes in consecutive open channel bends as the result of the presence of centrifugal force. Parameters such as water surface level, the transverse and depth velocity distribution, secondary flow and separation zones deeply depend on bend angel and radius. This paper presents an experimental and numerical study of the flow patterns in a consecutive open channel bend.The numerical modelling was carried out using the finite volume method. In this numerical study, the Reynolds stress model was used to predict the turbulence, and the volume of fluid (VOF) method was used to simulate the water free surface. The numerical results were verified against data from a program of experiments conducted in this study. A comparison between the experimental data and the results of the numerical model showed that the Reynolds stress model and VOF methods are capable of simulating the flow pattern in the consecutive open channel bends. The results showed that along a consecutive bend, the maximum flow velocity always occurs near the inner wall and in such bends the effect of the secondary flows is not limited to the sections within the bend. Also the horizontal velocity distribution in the second bend is effected by the Froude number and Reynolds number at first curved entrance, as well as the length of the connecting section of two curves.