Forces Acting on the Seabed around A Pipeline in Unidirectional Ocean Currents

In this study, the hydrodynamic forces acting on the seabed around the pipeline in unidirectional ocean currents have been investigated numerically. Two types of seabed are considered, i.e., plane and distorted seabed. The influences of gap between pipeline and seabed on the distribution of forces along the seabed are studied in detail. Computational results show that the pressure at the upstream side of the pipeline gradually decreases and the pressure difference between two sides of the pipeline presents a declining trend with the increase of gap between pipeline and seabed. For the pressure distributions between the distorted seabed and the plane seabed, a double-peaks distribution is observed for the case of distorted seabed, but only one peak exists for the plane seabed. With the increase of gap between pipeline and seabed, the value of peak shear stress along the distorted seabed at the upstream side gradually decreases and the one at the downstream side varies slightly. When the gap ratio reaches 0.7, the peak shear stress at the upstream side of the pipeline already decreases to a normal level for the case of distorted seabed, while the peak shear stress at downstream side is still a large one for the distorted seabed.