In this paper an attempt has been made to study the effects of floodplains width and discharges on flow field in prismatic compound channels. A three-dimensional Computational Fluid Dynamic (CFD) model is used to predict the velocity distribution, secondary flow circulation and boundary shear stress in prismatic compound channels with various floodplains widths. The ANSYS-CFX software and three different turbulence models, k-e, k-e Explicit Algebraic Reynolds Stress Models (EARSM) and Eddy Viscosity Transport, are used to solve Reynolds Averaged Navier-Stokes equations. The results of the numerical modeling were then compared with experimental data on prismatic compound channels with 100 mm, 200 mm, 300 mm, and 400 mm floodplain widths. The study shows that all turbulence models are capable to predict the depth-averaged velocity in prismatic compound channels, fairly well. However, to compare with the velocity distribution, discrepancy between experimental data and boundary shear stress calculated by numerical modeling are high. Also only k-e EARSM model is able to predict secondary flow circulations.
