Effects of Pile Dikes on Flow Retardation and Sediment Transport

Abstract

A mathematical model for defining lateral distributions of fluid velocity and suspended sediment concentration in straight channels with pile dikes near the banks is presented. Singular perturbation and matched asymptotic expansion techniques are employed to derive the distributions. It is found that suspended sediment is transported toward the pile dike region due to lateral turbulent diffusion, the amount of which is predicted by the theory. Laboratory work has revealed that the lateral diffusivities of fluid momentum and suspended sediment are identical with those observed for flows without pile dikes. The vertical diffusivity of suspended sediment is found not to be affected by pile dikes. The laboratory tests support the present model.