Lagrangian coupling two-phase flow model to simulate current-induced scour beneath marine pipelines

This paper presents a Lagrangian coupling two-phase flow model for simulating scour processes beneath a marine pipeline with respect to the sediment and fluid phase interactions. Smoothed Particle Hydrodynamics (SPH) capability is employed to simulate sediment and fluid particles movement, respectively as the Newtonian and non-Newtonian fluids in the framework of two-phase flow modeling. The Sub-Particle Scale (SPS) model also is closured to the fluid phase solver to account for the turbulence effects. The soft contact approach is incorporated in the sediment phase to simulate the interparticle collisions during the local scouring. Following to the Lagrangian coupling model development, the current-induced scour beneath a pipe at tunnel erosion and early stages of lee-wake erosion were explored and then compared with the experiments. The obtained results illustrated the efficiency of the proposed two-phase flow model to reproduce the scour profiles evolution up to the early stages of lee-wake erosion. Within the presented model, the parameters such as pressure field and non-dimensional sediment transport rate beneath the pipe were also estimated.

▸ A new Lagrangian model is developed to simulate current-induced scour near a pipe. ▸ SPH capability in the framework of two-phase flow is used to model sediment and fluid phase. ▸ Sediment and fluid phase is described as the Newtonian and non-Newtonian fluids. ▸ Soft contact model is closured to sediment phase to model the interparticle collisions. ▸ At tunnel erosion the maximum sediment flux increases with the depth of scour hole.