Author(s): Mani Golparvar Fard; Abbas Yeganeh-Bakhtiary; Liang Cheng
Linked Author(s):
Keywords: DEM; Local scour; k-ε turbulence model; Two-phase flow model
Abstract: A two-phase flow model is presented for simulating early stages of local scour due to steady current under offshore pipelines. Fluid phase is computed with solving Reynolds Averaged Navier-Stokes (RANS) equations in conjunction with a standard k- ε turbulence model for turbulence closure using Finite Volume Method in a Cartesian coordinate system. Seabed under pipeline is treated as an assembly of discrete sand grains, in which local scour is introduced as the motion of granular media under action of unsteady flow. Motion of every sand particle is traced with a numerical code based on Distinct Element Method (DEM), in which the frequent interparticle collision is described with spring and dashpot system. Laboratory measurements have been conducted to calibrate and verify model parameters. Numerical experiments evident that interparticle collisions of moving sand grains induce a predominant micro-mechanism on early stages of local scour around offshore pipelines and it is concluded that two-phase modeling, provides a precise simulation on sediment transport occurring in local scour under offshore pipelines.
Year: 2005