Transient flow: flow-induced vibrations
Jetties or drilling platforms usually stand in the water on piles. Flowing water exerts forces on the part of the piles that is located under water, possibly causing vibrations. We distinguish between vortex-induced and flow-induced vibrations. It is important to deal with these forces and the stresses caused by them, since they can lead to component failure.
The vibrations are caused by the interaction between the moving fluid and the pile. For example, flow around a pile can lead to the formation of a Karman vortex street. The detachment of these vortices causes a change in the flow direction. In the worst case the vortex shedding frequency corresponds to the natural frequency of the pile.
The GUNT model HM 162.61 “Vibrating piles” enables the observation of a single vibrating pile. Furthermore, there are two parallel piles that stand transverse to the direction of flow, and which are made to vibrate by the flow. The distance between the piles can be varied. If the distance is too small, there will be coupled vibrations between the two piles.