Numerical simulation of the equilibrium profile of local scour around submarine pipelines based on renormalized group turbulence model

The equilibrium profiles of local scour around submarine pipelines are simulated numerically by the renormalized group (RNG) turbulence model based on the finite element method and unstructured triangle grid system for the irregular boundaries. For the moving seabed due to the local scour, a method of fitting moving boundary with pre-meshed grid lines are introduced to the present mathematical model for capturing the equilibrium profile. Considering the complex configuration and notable slope of seabed, the incipient criterion of shear stress for sediment is modified based on the shields parameter. Two cases are employed to validate the proposed numerical model and the numerical results have shown a favorable match to the experimental data. It proves that the RNG turbulence model is capable of predicting the equilibrium profile of local scour around submarine pipeline. The bed shear stress is the dominant factor in terms of the configuration of local scour profile.