• Sunil A S
• Tide P S

Estimation and reduction of vortex induced loads on risers caused by ocean currents on long cylindrical structures like marine risers is a critical issue for offshore ventures. The complex vortex induced motions of the marine risers makes it difficult for researchers to predict the life and reliability of these risers. This paper investigates the nature of vortex induced vibrations created by ocean currents and ways to suppress the adverse effects by making a change in structural configuration. An Unsteady RANS simulation is used for the estimation of vortex induced loads on a long cylindrical marine riser. Shear Stress Transport (SST) k-ω turbulence model is used in this investigation to study the changes in turbulent characteristics accurately. The impact of the ocean currents on structure is investigated on a bare cylindrical structure and one with modified structural configuration. The intensity of Vortex Induced Vibration (VIV) at different conditions is analysed in terms of Strouhal number. It is found that the change in structural configuration can significantly reduce magnitude of vortex instabilities around the cylindrical marine structure. The results were found to be in reasonable agreement with the available data in the literature. The investigation in this paper can be applied to improve understanding of the vortex shedding phenomenon on marine risers and to estimate the vortex induced forces on marine risers.

Marine Riser, Strouhal Number, Vortex induced vibration, Turbulence, Structural configuration

"An Investigation on Reduction of Vortex Induced Loads on Marine Risers", International Journal of Emerging Technologies and Innovative Research (www.jetir.org), ISSN:2349-5162, Vol.6, Issue 4, page no.116-123, April-2019, Available :http://www.jetir.org/papers/JETIR1904G78.pdf

"An Investigation on Reduction of Vortex Induced Loads on Marine Risers", International Journal of Emerging Technologies and Innovative Research (www.jetir.org | UGC and issn Approved), ISSN:2349-5162, Vol.6, Issue 4, page no. pp116-123, April-2019, Available at : http://www.jetir.org/papers/JETIR1904G78.pdf