The fluid-structure interaction (FSI) is the interaction of some movable or deformable structure with an internal or surrounding fluid flow. Fluid-structure interactions can be stable or oscillatory. In the oscillatory interactions, the induced deformation in the solid structure causes it to move so that the deformation source is reduced and the structure returns to its previous state only for the process to be repeated.
Fluid-structure interactions are a crucial consideration in the design of many engineering systems, eg. Airplanes, engines and bridges. Failure to consider the effects of oscillatory interactions can be catastrophic, especially in structures comprising materials susceptible to fatigue. Tacoma Narrows Bridge (1940), the first Tacoma Narrows Bridge, is probably one of the most infamous examples of large-scale failure. Aircraft wings and turbine blades can break due to FSI oscillations. The fluid-structure interaction must be taken into account for the analysis of aneurysms in large arteries and artificial heart valves.
A cane actually produces sound because the system of equations that governs its dynamics has oscillatory solutions. The dynamics of sheet valves used in two stroke engines and compressors is governed by FSI. The act of "blowing a raspberry" is another example. Fluid structure interactions also occur in movable containers where the liquid oscillations due to vessel movement impose substantial magnitudes of forces and moments on the vessel structure which adversely affect the stability of the container transport system .