As meta-stable motions transverse to fluid flow in slender bluff-bodied structures, Vortex-Induced Vibrations (VIV) are mostly determined by three-dimensional (3D) geometric and relativistic changes that evolve in the structure. Simplistic models of the structure ignore these key physical principles.
In a 2014 OMAE paper, we introduced the key physical concepts for simulating VIV in a horizontal-oriented slender structure (pipeline). In a 2015 OMAE paper, we re-oriented the same structure vertically to simulate VIV in a vertical riser.
In this paper, one or more of the following variations in the vertically-oriented riser will be made, in order to judge the physical effect each variation has on the character and distribution of VIV along the riser:
• Cyclically move the upper end of the vertical riser
• Change into an S-shaped riser by adding weight/buoyancy
• Disconnect the lower end of the S-shaped riser
The simulations help show and reinforce the following mechanical concepts of VIV
• How gravity and fluid drag evolves a 3D shape in the riser
• How this shape creates specific structural flexibilities
• How these flexibilities set the stage for specific VIV
• How tension and end conditions are vital to VIV behavior
