Numerical simulation of local scour around underwater pipeline

Local scour is the main cause for the damage of underwater pipeline. In this paper, a two-dimensional numerical model of local scour around underwater pipeline is developed via the user defined function (UDF) in FLUENT software. In this new model, the governing equations for the flow model and sediment transport model are solved by finite volume method and finite difference method respectively. The critical Shields number acts as the incipient motion criteria of sediment, and the morphological change in the sandy bed caused by bed-load transport is simulated by dynamic mesh method. Based on this model, the local scouring processes around underwater pipeline at various gap ratios are simulated, and local scour around underwater pipeline is also conducted in the laboratory. The agreement between the experimental results and numerical results shows that present numerical model can simulate the scouring process around underwater pipeline accurately. Besides, at the early stage, the maximum scour depth increases sharply and later reaches to an equilibrium value. © 2014 ejge.