The behavior of a high mass ratio filament freely hanging in a fluid flow is experimentally and theoretically investigated. The experiments are performed in a horizontal wind tunnel using silicon filaments horizontally clamped at their upstream ends. We observed, at low flow velocity, static equilibrium states. Then, above a critical value of the velocity, the filament exhibits regular oscillations in a vertical plane. The theoretical analysis consists first to solve the governing equation for the stationary equilibrium states and then to analyze the stability of these solutions relatively to small perturbations. Comparisons between experimental and theoretical results reveal a good agreement. Effects of the length and diameter of the filament on the static or dynamical behavior have also been considered.
Interactions of flexible elongated bodies with flows are encountered in many domains as different as ocean engineering (towing cables, mooring lines, …), civil engineering (e.g. cables of suspension bridges or hanging roofs) or biomechanics as for instance in fish swimming (e.g. the flagellar and anguilliform swimming). Numerous studies have considered cases of low to moderate values of the mass ratio μ, where μ is defined as the "moving mass" (i.e. the mass of the structures plus the added mass of the moving fluid) divided by the displaced mass of fluid. Such situations are commonly encountered in ocean engineering where structures have mass ratio μ of the order of 10, at the most. In this case, periodic vortex shedding is responsible for vibrations of structures. References to this well-known phenomenon, referred to as vortexinduced vibrations (VIV), can be found e.g. in Govardhan and Williamson (2000), for the vibrations of an elastically supported rigid cylinders, and for flexible cylinders, in series of papers by Karniadakis and co-workers (see e.g. Evangelinos, Lucor and Karniadakis, 2000).
