Farshi, Fatemeh
PhD Graduate
AnalyticalNumerical Modeling of Boundary Shear Stress Distribution in Curved Compound Channels
Student Name 


Supervisors 
Abdolreza Kabiri Samani Mohammad Reza Chamani 

Date 
2018 



Keywords 
Boundary shear stress Depthaveraged velocity Secondary currents Compound channel Open channel bend Momentum transfer coefficient 
Abstract
Three previous researches were combined to develop an analytical model for evaluation of boundary shear stress in compound open channel bends. In the present model, perpendicular volumetric elements are generated in all cross sections of a bend. Each element represents an equation with two parameters as secondary current parameter and momentum transfer coefficient, standing for acceleration and apparent shear forces. For each cross section with N elements, N equations with N unknowns of streamwise depthaveraged velocity, are derived. The boundary shear stress distribution is then calculated using the DarcyWeisbach relationship. Simultaneous effects of centrifugal force, floodplain interferences, and variation of the depthaveraged velocity are combined in an analytical model to derive a relationship for estimating the secondary current parameter and the momentum transfer coefficient in bends of the compound open channels. These parameters are evaluated, using the experimental data. To generalize the obtained relationships, numerical modelling is performed using an open source CFD software, namely OpenFOAM. In the present study, the Reynolds Averaged NavierStocks equations (RANS) are solved, and a singlephase solver, simpleFoam, is applied with an appropriate boundary condition on the freesurface. The SST ke turbulent model is applied for turbulence modelling of the flow field. To obtain general correlations for the hydrodynamic characteristics of the flow such as the velocity components, different numerical models are developed. Accordingly, all the present numerical results, as well as the available experimental data are used to derive correlations for the secondary current parameter and the momentum transfer coefficient in curved compound open channels.