Investigation of Changing the Width of Flood Plains and Discharges on Secondary Flow in Prismatic Compound Channel

Velocity in a main channel is much higher than the floodplain in compound channels. This leads to the transfer of momentum between the main channel water and that of the floodplain. The relative “pull” and “drag” of the flow between faster and slower moving sections of a compound channel، complicates the momentum transfer between them. This momentum transfer also causes a secondary flow in compound channels. Considerable research on physical models for the behavior of the compound channels with different widths of the main channel and floodplain have been done by Shiono and Knight [1]، and Myers and Lines [2]. These researches help to understand the complex pattern of flow and boundary shear stress that has a significant role in momentum transfer between main channel and floodplain. Extensive studies have been for combination parameters of flow field in curved channels with compound channels as well as done in a sinusoidal compound channels. Toebs andsooky Studies in this direction can be pointed out [3]. In addition to compound channel، another locations that the secondary flow has an important effect on behavior of flow filed are in the channels and rivers bends. Some of flow characteristics such as secondary flow power and vortices power can assist to better understanding of flow filed in bends. Despite of expanded using of these characteristics in bends، they haven’t used in compound channel too much. In this research، the flow filed was simulated using different turbulence models and verified by experimental data in prismatic compound channel. Then the secondary flow power and vortices power of secondary flow in compound channel were computed.