Investigation of local scour around two vertical piles by using numerical method

Abstract

Local scour around two vertical piles is investigated numerically. A three-dimensional finite element solver is used to conduct the numerical study. The flow model is based on the three-dimensional Reynolds Averaged Navier-Stokes (RANS) equation by using the SST k-ω turbulence model closure. As for the scour model, both suspended load transport and bed load transport are considered. The numerical model is validated against (1) flow over smooth bed (2) local scour around one vertical pile by comparing with published data. In order to add weight of evidence on the effectiveness of present numerical model, two experimental tests are carried out. Present numerical model works well to predict the velocity and local scour around piles by comparing with published data and present experiment. Then the numerical model is used to study local scour around two vertical piles in tandem, side by side and staggered arrangements. The dependence of scour depth at the upstream side of the piles on gap ratio is discussed. Moreover, the time scale of scour under various gap ratios is investigated.