Bridge Afflux Predictions Using the Lattice Boltzmann Method

摘要

The maximum water surface change just upstream of a bridge is termed the afflux in hydraulic engineering. An initial attempt at using the lattice Boltzmann method (LBM) to study afflux has been made in this paper. The LBM representing the 2D nonlinear shallow water equations (LABSWE) is applied to both single-span and multi-span bridges with a free water surface without introducing additional empirical coefficients. For a single-span bridge, three configuration parameters, blockage ratio, skewness and eccentricity, are investigated by the LBM; for a multi-span bridge, the influence of pier shape and skewness on afflux is also tested. The results agree closely with those of traditional methods, which illustrates that LABSWE is not only able to compute average afflux but also to show the afflux distribution across the section and the flow distribution around the obstruction.