University of Roorkee, Roorkee.
It is well-known that flow can separate from the side walls of an open channel expansion even though it is well streamlined, particularly when the angle of divergence is high. Here separation of flow occurs as a consequence of the boundary-layer growth. The boundary-layer develops very rapidly along the curved wall due to the positive. pressure gradient. In this paper, experimental data on the development of the turbulent boundary-layer along the arc length of a diverging wall as obtained in a flume are presented.
The transition geometries selected for the present study were a linear expansion and two hyperbolic expansions given by Sarvashri A.C. Mitra and U.S. Chaturvedi for the design of irrigation works. The Fronde number of the approach flow was of the order of 0-7. The angle of divergence was kept as 10° and the fluming ratio 50 per cent. Velocity profiles in the boundary-layer were obtained with a pitot tube. The separation point was also observed in the experiments by injecting a dye on the side walls. The experimented data had, been analysed and compared with semi-theoretical methods available for predicting the separation of a turbulent boundary-layer.
