ABSTRACT
Experiments have been performed in compound channels with three different diverging angles (5.93°, 9.83°, and 14.57°) to study the behaviour of flow in the diverging compound section. In this research, depth-averaged velocity, water surface profile and discharge distribution have been studied for six different relative flow depths (0.15, 0.20, 0.25, 0.30, 0.40 and 0.50) cases. The new experiment shows that, in this diverging geometry: (1) for low relative flow depth cases, water surface profile decreases from upstream to downstream with small gradient and for high relative flow depth cases it increases significantly; (2) depth-averaged velocity distribution in the main channel region is found to be of similar magnitude for low relative flow depths from upstream to downstream, but for high relative flow depth cases it decreases. An empirical model has also been suggested to compute percentage discharge distribution in main channel region by considering four non-dimensional geometric parameters such as width ratio, relative flow depth, flow aspect ratio, and relative longitudinal distance. Along with the present experimental dataset, other published data have been used to develop the model. The new model found to give satisfactory results when compared with experimental values. Different statistical error analysis has been performed to check the strength of the present model in predicting the percentage floodplain discharge distribution.
