Sloshing experiments: Large scale circulations and instabilities

The sloshing motion of fluids occurs in partly filled containers subjected to vibrations or oscillations. For example, sloshing can be catastrophic in spacecraft tanks, but is useful to damp energy e.g. in skyscrapers following an earthquake. In most applications, the shift of mass and impact on the container walls are the most relevant phenomena. Many studies have focused on these effects, studying the details of their occurrence for complex or shallow tank geometries and developing nonlinear models for simulations. In this talk, we take a different approach and revisit experimentally the fundamentals of deep water sloshing in a thin rectangular container under harmonic oscillation. Taking advantage of the quasi-two dimensional nature of the flow, we correlate the surface motion to the flow field in the bulk. We unravel nonlinear effects like hysteresis and shift of the resonance frequency that are known from other complex systems. In the vicinity of the resonance frequency, we observe large-scale circulations, which fill the entire container and enhance mixing.