Overbank flow in symmetrically narrowing floodplains

Experimental data are presented for flow in compound channels with symmetrically narrowing floodplains. In such a geometry, the flow behavior presents similarities with the more complex flow in a meandering compound channel, yet without the curvature effects, because of mass transfers between the floodplains and the main channel, and secondary currents induced in the main channel. An estimation of the momentum transfer generated by the mass transfer is found significant compared to the frictional losses. It mainly depends on the geometrical parameters and is practically independent of the friction slope. Free-surface profile computations are performed with the exchange discharge model (EDM) to incorporate the effects of the momentum transfer in terms of an additional head loss. Agreement was found between measured and computed water surfaces, thus validating the EDM approach.

[1]  P. Ackers HYDRAULIC DESIGN OF TWO-STAGE CHANNELS. (WINNER OF 1993 COOPERS HILL WAR MEMORIAL PRIZE). , 1992 .

[2]  R. Sellin,et al.  Factors Affecting Conveyance in Meandering Compound Flows , 1993 .

[3]  D. Knight,et al.  Turbulent open-channel flows with variable depth across the channel , 1991, Journal of Fluid Mechanics.

[4]  Didier Bousmar,et al.  Flow modelling in compound channels : momentum transfer between main channel and prismatic or non-prismatic floodplains , 2002 .

[5]  R. Sellin,et al.  Behaviour of meandering two-stage channels , 1993 .

[6]  R. French Open Channel Hydraulics , 1985 .

[7]  Y. Zech,et al.  Momentum transfer for practical flow computation in compound channels , 1999 .

[8]  K. Babaeyan-Koopaei,et al.  Two-Dimensional Solution for Straight and Meandering Overbank Flows , 2000 .

[9]  Hasan Kadhem Jasem Flow in two-stage channels with the main channel skewed to the flood plain direction , 1990 .

[10]  R. H. J. Sellin,et al.  SERC flood channel facility: skewed flow experiments , 1990 .

[11]  P Ackers,et al.  HYDRAULIC DESIGN OF TWO-STAGE CHANNELS , 1992 .

[12]  R. Sellin,et al.  DEVELOPMENT OF A SIMPLE METHOD TO PREDICT DISCHARGES IN COMPOUND MEANDERING CHANNELS. , 1993 .

[13]  D. Knight,et al.  Stage-Discharge Assessment in Compound Meandering Channels , 1999 .

[14]  K. Shiono,et al.  Complex flow mechanisms in compound meandering channels with overbank flow , 1998, Journal of Fluid Mechanics.

[15]  R. Sellin A laboratory investigation into the interaction between the flow in the channel of a river and that over its flood plain , 1964 .