Investigation of Scour Around Two Side-by-Side Piles with Different Spacing Ratios in Live-Bed

Abstract

AbstractIn this study, a developed model is employed for numerically investigating scour around a group of two identical side-by-side piles. The model benefits from a coupled approach between a hydrodynamic and a morphodynamic model which is successfully validated for predicting scour around a single circular pile. The hydrodynamic model solves unsteady Reynolds-Averaged Navier-Stokes (RANS) equations in combination with the k-ω-SST turbulence closure model. The morphodynamic model entails bedload and suspended load sediment transport models for non-cohesive sand. The morphological evolution of the bed due to the sediment transport fluxes is expressed by a means of a mass-balance equation. The model is run for two side-by-side piles with three different spacing ratios G/D = 1, 2, and 3, where G represents the distance between the piles and D is the pile diameter, under steady-current flow and live-bed conditions. The results of the investigation reveal an inverse correlation between the spacing ratio and the scour hole depth adjacent to piles. The results are generalized and an equation is obtained for equilibrium scour hole depth as a function of the spacing ratio.KeywordsScourSide-by-side pilesCFDSediment transport