Numerical study of the effect of interaction of bridge pier and rectangular abutment on flow characteristics

One of the important issues in bridge design is investigating the influence of vicinity of bridge abutment and pier on flow characteristics around it. In the present research, Flow-3D software was used for numerical modeling of a rectangular abutment in a rectangular channel in two situations (presence of one cylindrical pier and two cylindrical piers). For validation of the modeling results, three-dimensional components of flow velocity around the bridge abutment and piers were obtained from two sets of valid experimental data. After comparison of the experimental data and numerical results, it was found that RNG model for abutment and bridge piers (with coefficient of determination (R2) of 0.963 and 0.871, respectively) had better performance with respect to K-ε and LES turbulence models. Some of the flow characteristics such as turbulence energy and bed shear stress were investigated, too. The flow turbulence-energy of both models (rectangular abutment in the vicinity of single-pier and double-pier) was equal to and three times of the control model, respectively. Also, bed shear-stress of rectangular abutment in the vicinity of single cylindrical-pier was maximum and four times that of the control model. Investigation of the distance between rectangular abutment and bridge pier, considering the control model and other research results, indicated that closer distances are safer.