Flow Past of a Drilling Riser System with Auxiliary Lines in Laminar Flow

Vortex-Induced Vibration (VIV) has emerged as a crucial problem that may arise during a drilling operation, which could result in riser failure. Engineers focus on drilling riser's flow characteristics and controls with the intention of improving the drilling environment. Auxiliary lines or control rods are usually placed around the main drilling riser to suppress the VIV. However, the issue related to the flow past drilling riser system with auxiliaries has yet to be resolved. The flow characteristics around a riser system with auxiliaries were analysed in this research. The simulations were conducted using Computational Fluid Dynamics (CFD) software, Altair AcuSolve. This work focuses on the influence of various gap ratios (G/D) and diameter ratios (d/D) on the vortex interaction. A main cylinder with six auxiliary lines was modelled with G/D of 0 to 2.0 and d/D of 0.10 to 0.60 to simulate the riser system. The simulations were carried out at Reynold Number of 200 in the laminar flow regime. The results revealed that the hydrodynamic forces decreased when d/D and G/D increased. The vortex shedding was significantly reduced for auxiliary lines with G/D between 0.3 and 1.4. The numerical simulation results indicated that the vortex interaction in the wake region was, and the hydrodynamic forces were reduced due to the auxiliary lines configurations. The findings of this study are intended to contribute a new CFD simulation result for a better prediction of VIV on a drilling riser with auxiliary lines.