Numerical simulation of flow pattern at a divergent pier in a bend with different relative curvature radii using ansys fluent

Abstract

This paper has modeled the three-dimensional flow around piers at river meanders under rigid bed conditions in three dimensions. ANSYS FLUENT software was employed to carry out the simulation. The research was conducted in a 180-degree bend accompanied by cylindrical piers with a diameter of 5 cm and an inclination angle of 21 degrees under rigid bed conditions. Results of comparisons indicated that this model may be used in simulation of the flow pattern around inclined bridge piers in bended channels with an acceptable accuracy. Further, the work was followed by an investigation of the effect of the parameters influencing the physics of the problem, the bend's relative radius of curvature, the location of the piers within the 180-degree bend, and the ordering of the piers relative to the flow direction in order to analyze the flow pattern. Results demonstrated that increasing the relative curvature radius as well as the bend reach would reduce the tangential velocity values; the minimum tangential velocity value occurred at a relative curvature radius of 5. Placement of the pier group in a streamwise direction resulted in the maximum secondary flow power occurring at the 60-degree position for approximately 18.8%, while installing them transverce to the flow led to the maximum secondary flow power occurring at the 120-degree position for 14.2%. A comparison of vorticity in a perpenduclar and a streamwise position demonstrated that vorticity values at the 60 and 120-degree positions in both cases were larger than the corresponding values at the 90-degree position.