THREE-DIMENSIONAL NUMERICAL SIMULATION FOR LOCAL SCOUR AROUND A CYLINDRICAL BRIDGE PIER

摘要

Bridge scour is one of the main causes of bridge failure. Combined with wall function, standard k-ε turbulence model was used in this paper to simulate the threedimensional flow fields around a cylindrical bridge pier. The critical shear stress was regarded as the judging standard of incipient motion of sediment. Bed-load transport model was employed to calculate the instantaneous change of the elevation of the riverbed, with consideration of the influences of bed-slope to the bedload transport rate and the critical shear stress. σ-grid was employed to fit the changing river-bed and the changed grid was used as the computational grid in the next time step. Then, the change of the river-bed was calculated again. Repeating this procedure, the evolution process of scour hole around the cylindrical bridge pier was obtained. Comparing the numerical results with the experimental results, it was shown that they agree well. Numerical model accurately calculated the maximum depth of scour hole around the bridge pier.