Vortex scouring process around bridge pier with a caisson

An experimental investigation to predict the characteristics of scour vortices related to the scour depth of caisson piers was conducted. Two median size sediments were used as bed materials. Three types of piers, namely a cylindrical pier, a cylindrical pier with a caisson, and a nose pier were considered. The size and the rotational speed of the primary vortex were measured and correlated to the flow and pier parameters. The vortex power available to scour the sediment is related to the power provided by the vortex in the scour process. The equilibrium scour depth was predicted based on the concept of power available in the primary scour vortex equal to the resisting power of sediment in the scour hole. The prediction of the scour depth agrees well with literature data.