Numerical Simulation On Flow Field At Bridge Piers During Ice Period

Ice jam is the phenomenon when ice or crushed ice cluster in the river.Because of the congestion of the clustered ice, the pack-ice will congest, whichwill then form ice sheet. Formation of ice sheet will enlarge the region of flow,ice floating in the river will decrease the flow velocity, increase the crosssection of flow, and raise the water level. Bridges and piers in the river willeffect the force of the existing ice sheet, they squash the river and provide agood groundwork for ice-clustering, which will further threaten the security ofthe bridges. Local scour depth around pier under the ice sheet is an importantcause of bridge damage, judging from the above analysis, research of flow statearound piers will contribute to the study of piers’ local scour. There have been alot of indoor open channel and sink model experiments, field measurements anddata calculations performed by scholars and Researchers around the world. Theexisting studies mainly focus on flow character and turbulence intensity arounda single pier, however, studies hardly extent to the situation when there is singleor tandem piers in a frozen river.We chose the CRREL sink as the model of this research, based on themultiphase flow theory, by using Fluent software, we built a3-D standard turbulence data model of flow field applied on piers by flow under frozenconditions. The research deals with influence and differences of flow fieldapplied on piers by flow under different operation conditions when there is asingle row or tandem of cylindrical piers, the variable conditions includediameter of piers, flow velocity at the entrance and the thickness of the ice. Thesimulation result shows that both influence and velocity are larger when there isa single row of piers than that of tandem piers; under frozen conditions, thescour more severe if the velocity increases, the dynamic pressure around thepiers rises with the thickness of the ice, thus scouring becomes more vigorously;a bigger diameter of piers means that the cross section of flow will be furthercompressed, which will result in a larger velocity and in turn increase the scour.Above all, by comparing with the data form CRREL sink experiment, thediscipline summarize from our numerical simulation can accord basically withexperimental rules.