Numerical Simulation of Flow past a Marine Riser

Abstract

The increasing worldwide demand for oil / gas means that offshore platforms are being constructed in more marine areas. Cylindrical structures such as SPAR platforms, risers and pipelines are commonly being used in oil / gas extraction, especially in harsh environments such as deep sea production operations. We aim to discover the hydrodynamic behaviour of the flow around a curved cylinder in ocean currents. In the past several decades, the fluid mechanics of the cylindrical body flow has been widely studied. However, there are few vortex control methods applied at the connection between the cylindrical structures and the seabed. In this research, a straight cylinder will be used for the validation of the simulation method. A curved cylindrical geometry with two bending directions will be simulated in uniform flow and logarithmic flow profiles at three maximum Reynolds numbers (1.5×105, 2.6×105 and 3.8×105). K-epsilon has been used as the turbulent viscosity model, which is one of the most common turbulence models to solve the Reynolds Averaged Navier-Stokes for the flow. The results show that a curved cylindrical structure will have reduced vortex shedding compared to a straight cylinder in the same flow.