Analysis of the wake dynamics of stiff and flexible cantilever beams using POD and DMD

• Wake structures for both stiff and elastic cantilevers are investigated.
• The topology of the wake is outlined.
• Several competing modes are found in the wake.

The wake flow behind a cantilever beam of quadratic cross-section at a Reynolds number of 50,000 is investigated using detailed simulations. Two cases are considered, the first one using a stiff beam and the second one with a beam allowing for elastic deformation due to the hydrodynamic forces. The flow is simulated using an implicit large eddy simulation (ILES) approach in OpenFOAM and the structural deformation of the beam is found from a non-linear finite element approach using OOFEM. The motion of the fluid mesh due to the structural deformation is handled by an ALE method. The wake structures are investigated using proper orthogonal decomposition (POD) and dynamic mode decomposition (DMD) of the flow field. The results show that apart from the wake structures originating from the vortex shedding there is also a low frequency mode, which is an oscillatory motion in the stream-wise direction, present.