A review of the existing research on the interaction between a pipeline and an erodible bed exposed to waves and/or currents is presented. The review covers three topics: scour, liquefaction, and lateral stability of pipelines. The basic mechanism that leads to scour in two-dimensional (2D) and three-dimensional (3D) cases is first described, as deduced from small-scale laboratory experiments. The onset of scour from piping and the developing tunnel erosion are among the processes described. The lateral expansion of the scour hole along the pipe is described, also based primarily on small-scale laboratory experiments. The state of the art of the mathematical/numerical modeling of the scour processes is presented. The associated self-burial of the pipe is described and compared to field observations. In addition to scour, liquefaction may also constitute a risk for pipeline stability. The cause of liquefaction and the resulting consequence for pipeline stability in a natural environment are discuss...

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Pipeline–Seabed Interaction

Vortex-induced vibration suppression of a main circular cylinder with two rotating control rods in its near wake: Effect of the rotation direction

https://backend.orbit.dtu.dk/ws/files/202653469/1_s2.0_S0378383919301784_main.pdf

Numerical investigation of wave-plus-current induced scour beneath two submarine pipelines in tandem

Numerical investigation of hydrodynamic characteristics and local scour mechanism around submarine pipelines under joint effect of solitary waves and currents

As a new type of submarine pipeline, the piggyback pipeline has been gradually adopted in engineering practice to enhance the performance and safety of submarine pipelines. However, limited simulation work and few experimental studies have been published on the scour around the piggyback pipeline under steady current. This study numerically and experimentally investigates the local scour of the piggyback pipe under steady current. The influence of prominent factors such as pipe diameter, inflow Reynolds number, and gap between the main and small pipes, on the maximum scour depth have been examined and discussed in detail. Furthermore, one formula to predict the maximum scour depth under the piggyback pipeline has been derived based on the theoretical analysis of scour equilibrium. The feasibility of the proposed formula has been effectively calibrated by both experimental data and numerical results. The findings drawn from this study are instructive in the future design and application of the piggyback pipeline.

Experimental and Numerical Investigation of Local Scour Around Submarine Piggyback Pipeline Under Steady Current

Local scour around two pipelines in tandem in steady current

The vortex shedding flow past two circular cylinders of different diameters is investigated numerically by solving the threedimensional Naiver-stokes equations using the Petrov-Galerkin finite element method (PG-FEM). The Reynolds number based on the free stream velocity (U) and the diameter of the large cylinder (D) is Re=1000. Simulations are carried out for a constant gap of 0.0625D and a constant diameter ratio of 0.45. The study is focused on the effect of position angle of small cylinder relative to the larger one on the three-dimensional flow, the force coefficients, the vortex shedding frequencies from the two cylinders and flow characteristics. As observed in the previous experimental studies, biased flow in the wake of the gap is observed when the two cylinders are in nearly side-by-side arrangement and it leads to significant reduction of the oscillation of the forces on the cylinders.

Shailesh Vaidya

Papers

Local scour around two pipelines in tandem in steady current

Local scour around two pipelines in tandem in steady current

Three-dimensional simulation of flow past two circular cylinders of different diameters