Vendredi 10 janvier 2025 à 11h00 ; salle des séminaires IRPHE
Abstract: During this seminar, I will present several surprising phenomena that can occur at a liquid interface under suitable experimental conditions. In a first part, I will show how high frequency vertical vibrations can be used to stabilize a liquid layer above an air cushion. Buoyant objects can moreover float at the lower interface in a way that will be discussed. Some generalization with non-vertical or spatially inhomogeneous shaking will also be considered. In a second part, I will discuss fluid-structure interactions through a simple experiment consisting in a ball stirred along circles at the water’s surface by a deformable string. The interaction between the string’s deformation and fluid’s back-action leads to a wide variety of ball’s trajectories that will be described. The existence of a Magnus force and its measurement through direct flow reconstruction and force equilibrium will be discussed. I will also describe the emergence of robust self-trapped states, in which the ball traps itself at the rotation center, as well as the impact of such states on the fluid’s mixing.