Forces on Marine Risers in Coexisting Environment
Publication: Journal of Waterway, Port, Coastal, and Ocean Engineering
Volume 114, Issue 3
Abstract
Experimental results for hydrodynamic loading from the combined effect of oscillatory motion and current on two productionriser configurations are presented. The riser systems tested consist of a single cylinder and a large center pipe surrounded by twelve satellites. The current is superimposed on the oscillatory motion in three directions: parallel; perpendicular; and oblique with a 45° angle. The experimental study showed a significant reduction in the drag coefficients when the oscillatory motion and the added current were parallel. The magnitude of this reduction depends primarily on the ratio of the maximum velocity of oscillatory motion to the steady current speed. The prediction of forces on marine risers using Morison's formula in a coexisting environment at low Keulegan‐Carpenter numbers yields unsatisfactory results due to vortex shedding. However, the use of this equation at high Keulegan‐Carpenter numbers in a coexisting environment was demonstrated to be safe and appropriate. The data and results of this study have shown that current strongly influerces the fluid loading of risers in the drag‐inertia dominated regime. Current has a profound effect on the drag and inertia coefficients used in the Morison equation.
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Information
Published In
Journal of Waterway, Port, Coastal, and Ocean Engineering
Volume 114 • Issue 3 • May 1988
Pages: 346 - 359
Copyright
Copyright © 1988 ASCE.
History
Published online: May 1, 1988
Published in print: May 1988
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