Two-Phase Simulation of Wave-Induced Tunnel Scour beneath Marine Pipelines

Abstract

An Eulerian two-phase flow model was presented and employed to investigate waveinduced tunnel scour beneath a marine pipelines. The model is based on the Euler-Euler coupled governing equations for the fluid and sediment phases, i.e. time-averaged continuity and momentum equations were solved for both phases with a modified k-ε turbulence closure for the fluid phase. Fluid-particle, particle-particle and fluid-structure interactions were implemented in the simulation. The model accounts for the interphase momentum exchange by considering the drag, lift and added mass forces. The flow model was validated against an oscillatory flow around an isolated cylinder and a cylinder close to a rigid wall. The two-phase model was also validated against an

Simulation of Wave-Plus-Current Scour beneath Submarine Pipelines

“…The earliest attempts to model scour beneath pipelines were made using potential flow models, whereas more recent attempts were carried out by solving the complete Navier-Stokes equations, either in the form of the Reynolds-averaged Navier-Stokes equations (RANS), or using Large Eddy Simulation (LES). Brørs (1999), Liang and Cheng (2005b), Liang et al (2005) Zhao and Fernando (2007), and Zanganeh et al (2012) succeeded in modelling the scour evolution beneath pipelines in steady currents and Liang and Cheng (2005a), Kazeminezhad et al (2012) and Fuhrman et al (2014) modelled the scour beneath a pipeline due to waves. Fuhrman et al (2014) demonstrated accurate scour time scales, while also managing to simulate the backfilling process caused by a change to milder wave conditions.…”

Scour patterns below pipelines and scour hole expansion rate

“…The result showed that the pore pressure responses to the current and waves were considerably different in different types of soil due to the variation in the properties of the soils. Kazeminezhad et al (2012) presented an Eulerian two-phase flow model for the waveinduced scour beneath the pipeline and observed the tremendous sediment transport in the high turbulence intensity after the onset of scour.…”

Numerical Investigation of Scour Beneath Pipelines Subjected to an Oscillatory Flow Condition

“…Apart from experimental studies carried out by Sumer and Fredsøe [2], Fredsøe et al [6], Cheng et al [7] and Qi and Gao [8], the scour process under waves at different KCs was also investigated using a stochastic method by Myrhaug et al [9] and numerical simulations by Liang and Cheng [10], Kazeminezhad et al [11], Fuhrman et al [3] and Li et al [12]. The main challenge in numerical simulations of the scour process is how to resolve the interactions among the flow, the sediments, and the structures.…”