Session: 04-03-03 Hydrodynamics

Paper Number: 103310

103310 - Hydrodynamic Forces of Subsea Small-Diameter Pipeline in a Deep/wide Trench 

Accurate predictions of the hydrodynamic forces on a pipeline or cable in a trench are of both fundamental and practical significance. Existing design guidance (DNV-RP-F109) enables forces to be estimated based on a simplified model of a pipeline in a trapezoidal trench with very limited dependence of hydrodynamic forces on incoming flow and some trench geometry parameters, such as the slope of the trench θ, the trench-width-to-pipeline-diameter ratio W* and the trench-height-to-pipeline-diameter ratio H*. The present study conducts a series of two-dimensional and three-dimensional direct numerical simulations of steady flow past a pipeline placed at the bottom of a smooth trench over a range of trench configurations (θ = 0⁰-45⁰, W*= 3-20 and H*=1-5). The Reynolds number based on incoming steady flow velocity and pipeline diameter is fixed at 3900, meaning that these results are a preliminary investigation of the problem rather than representing typical pipeline / cable / trench / flow conditions. The primary focus of this paper is to explore how the flow characteristics in the trench and hydrodynamic forces are affected by the trench configurations. The eventual outcome of this study is expected to be applicable to the stability design of subsea pipelines and power cables that are placed in seabed trenches that are natural, pre-lay or post-lay excavated and cover a much broader and more relevant range of cable/pipe, flow and trench configurations than available existing guidance.

Presenting Author: Zinan Liu The University of Western Australia

Presenting Author Biography: Education
2014.09-2018.07, BE in Harbor, Waterway and Coastal Engineering, Dalian University of Technology, China
2018.09-2021.07, MS in Civil Engineering, Dalian University of Technology, China
2021.08-, PhD, The University of Western Australia, Australia

Research interests
My research expertise covers from advanced numerical modelling in Computational Fluid Mechanics (CFD) to in-depth understanding of flow characteristics in the trench and hydrodynamic forces are affected by the trench configurations.

Authors:

Zinan Liu South China University of Technology
Liang Cheng The South China University of Technology
Chengjiao Ren The University of Western Australia
Terry Griffiths The University of Western Australia
Feifei Tong The University of Western Australia