Numerical investigation of local scour around tandem piers using proposed self-sustaining inlet turbulent boundary conditions

Abstract

Turbulent characteristics significantly affect the numerical results of local scour in tandem piers. The novel self-sustaining model was used to quickly develop homogeneous isotropic turbulence to maintain the consistency of the numerical and physical flow fields. The Reynolds averaged N-S equations, which are close to the standard k−ε turbulence model, were employed to solve the complex flow field around the bridge piers. The sediment transport model, combined with dynamic mesh updating methods, simulated the evolution process of the local scour for tandem piers. The results indicated that the maximum scour depth occurred at the upstream pier at different distances between the centres of the two piers (L/D). The scour depth reached its largest value when L/D = 4, and the maximum scour depth reached its minimum value when L/D = 2. When L/D > 5, the shielding effect can be neglected for downstream piers. In addition, based on the numerical simulation results, a shielding coefficient was established, providing a method for quickly predicting the local scour depth based on the scour depth of the isolated pier and a reference for the scour resistance design of bridges, offshore fans, and other structural foundations.