Tridimensional modeling of the flow around a submarine duct using computational fluid dynamics (CFD)

Abstract

Submarine pipelines are used in operations offshore drilling of wells and production of oil and natural gas. These ducts can be supported on the seabed carrying oil from a producing well to a floating production unit at the sea surface. They are referred to as submarine pipelines or flow lines while resting on the seabed, and when found suspended, connecting the seafloor to the production unit on the surface, are called risers. These pipelines are subjected to sea stream, waves and motion induced by the floating unit to which they are connected. Its interaction with the sea water creates two force components in the pipeline: the drag force (FD) and the transverse force (FL), respectively, in the incidence and perpendicular water directions relative to the duct. The transverse force makes the duct oscillate, phenomenon known as Vortex Induced Vibration (VIV). It is important for pipeline's design because it can speed the fatigue process in the pipe. In this work, Computational Fluid Dynamics (CFD) is going to be applied to solve the three-dimensional flow around an underwater pipeline section. It'll be considered two cases: first, with a stationary section condition; and second, section with forced motion into transverse direction of flow incident condition. Hydrodynamic drag and coefficient (CD), transverse force coefficient (CL) and the Strouhal number (St) are going to be obtained, analyzed and compared with literature's results. (AU)