VortexInduced

Vortexinduced refers to effects that arise from vortices formed in a fluid flow interacting with a body or structure. The most studied manifestation is vortex-induced vibrations (VIV), where alternating shedding of vortices from a bluff body generates fluctuating transverse forces that can excite structural modes.

In the typical mechanism, fluid flows past a bluff object such as a circular cylinder, producing pairs of counter-rotating vortices that are shed alternately from the sides. The shedding occurs at a characteristic frequency f that scales with flow speed U and a representative length D of the body, commonly expressed with the Strouhal number (St): f ≈ St · U / D. When the shedding frequency approaches a natural frequency of the structure, a lock-in or resonance-like condition can occur, amplifying responses and potentially causing fatigue.

Vortexinduced effects are observed in air and water and are important in engineering and design. Examples include tall chimneys, bridge piers, pipelines and risers, offshore platforms, subsea cables, and architectural elements exposed to wind or currents. In marine and offshore contexts, vortex-induced vibrations can govern fatigue life and need to be accounted for in installation and operation.

Mitigation strategies aim to disrupt vortex formation, shift frequencies away from structural modes, or increase damping. Approaches include fairings, helical strakes, fins or spoilers to reduce lift, dampers or tuned mass dampers, and design adjustments to alter natural frequencies or stiffness. Measurements rely on sensors, model testing (wind or water tunnels), and computational fluid dynamics to predict and analyze vortex-induced responses. The term encapsulates phenomena where fluid vortices drive mechanical or structural behavior.