Numerical comparison of stability and flow pattern over offshore pipelines in trench

초록

Offshore pipelines are to be stabilized against external loading mainly caused by wave and currents. As pipelines are placed in a trench, the forces acting on them are reduced considerably. The forces can be divided into three components, drag, interia and lift. To investigate the stability in various trench sections, the flow over the pipeline is numerically simulated and compared with experimental results obtained from PIV measurement. In the computation, Smagainskys eddy viscosity model combined with a truncated deductive model is applied to represent the SGS stress field in quadrilateral structured grid system. The stability for various trench conditions are addressed in terms of mean amplitudes of oscillating lift and drag, and reduction factors for each case are suggested for pipeline design.