This is probably the most common type of flow-induced vibration and is caused by oscillating flow separation from a structure. Circular cylindrical structures are particularly susceptible to VIV and breaking the circular or cylindrical symmetry of the structure, by using strakes for instance, is an effective way of reducing the amplitude of vibration and the resulting stresses. Galloping and Flutter - These vibration phenomena occur when the motion of a structure generates fluid forces that reinforce the vibration.
All noncircular structures are susceptible to galloping and flutter.
Examples include ice-coated power lines, aircraft wings, and marine structures with noncircular cross sections. SES has experience designing aerodynamically shaped piping structures for galloping. Motion of one tube generates a pressure field on the adjacent tubes which in turn causes those tubes to oscillate around their equilibrium position. In extreme cases this self-reinforcing motion can lead to high stresses at tube sheets and baffles, resulting in rapid fatigue failure. SES has experience designing arrays of circular and noncircular tubes to resist fluid-elastic instability.