Numerical simulation of the flow field around a stack of rings for bridge pier protection

The vortex generated around the bridge pier could cause severe erosion at the bottom of the pier, and threaten the stability of the pier during the flood events. This study applies the FLOW-3D model to simulate the flow characteristics around the bridge pier that has a stack of rings installed in front of it with a certain distance, for understanding the effect of a stack of rings on bridge pier protection. The arrangements of the stack of rings include two kinds of rings size (D = 4.5 cm and 6.75 cm), two kinds of geometrical shapes (regular triangle and circle), and three kinds of distances between the stack of rings and the bridge pier (L = 9.75 cm?19.5 cm and 29.25 cm). The simulation results show that the approaching flows is divided by the stack of rings into two sub-flows after setting the stack of rings for protecting the bridge pier. The two divided flows would disturb the flow condition and then form a wider slowvelocity area around the bridge pier. The impact caused by flow on the bridge pier is decreased by the stack of rings. The comparison of different arrangements shows that the arrangement of smaller ring size is better than that of larger one. Both triangular and circular shapes ofthe stack of rings could generate a large slow flow area in the downstream of bridge pier. The case of smaller distance (L = 9.75 cm) between the stack of rings and the bridge pier generates bigger shading area that would results better effect on pier protection.