Three-dimensional Analysis of the Effect of Attached-Abutment to the Channel Wall on the Hydraulic Parameters of Flow, Using Flow-3D Software

In the present research¡ three-dimensional flow in a rectangular channel¡ containing a bridge abutment¡ was simulated by using flow-3D software. For validation of the numerical results¡ three-dimensional components of flow velocity in the vicinity of the abutment were obtained from an experimental test. After comparison of the measured and numerical results¡ it was shown that RNG performed better (R2= 0.963¡ RMSE=0.02 and MAE= 0.03) than the other two turbulence models (LES and k-ε). The optimum mesh size was chosen based on the above results. Results revealed that it is necessary to consider return vortices and fluctuations in flow velocity in the vicinity of the abutment¡ especially in the downstream¡ for proper design and location of abutment geometry. Viscosity and energy of flow turbulence in the downstream of the rectangular abutment reached their maximum value and existence of the obstacle was more pronounced. It was shown that in the section after the abutment¡ simultaneous reduction of velocity and becoming negative¡ the viscosity had an increasing trend and reached up to 0.67 Pa sec. The section located in the middle of the abutment had minimum turbulence energy (0.00245 J/kg) and the next section had maximum turbulence energy (3.59 J/kg). Pressure variations around the abutment showed that maximum pressure (933 Pa) occurred in the previous section and minimum pressure (860 Pa) was seen after the abutment.