Dynamics of a Bouncing Droplet on a Faraday Wave-induced Bath

A droplet descending freely onto a vertically oscillating bath exhibits diverse dynamics depending on the strength of the applied acceleration. Weak forcing leads to coalescence, while stronger accelerations can induce bouncing, walking, or chaotic behavior. This study focuses on the intermediate regime in which the droplet undergoes sustained bouncing without coalescing. We run axisymmetric simulations using Basilisk to accurately resolve the droplet–bath interface dynamics. We construct a Weber–Reynolds number (We–Re) phase space to classify distinct bouncing behaviors. At low viscosity, the droplet exhibits periodic oscillations and regular bouncing, whereas increased viscosity leads to chaotic dynamics driven by bath instability. This transition is supported by FFT analyses, which reveal the emergence of multiple dominant frequencies, signaling the onset of Faraday wave generation. To further elucidate the droplet dynamics, we analyze the temporal evolution of kinetic energy, vertical centroid motion, shape deformation, and pressure variation within the air gap during droplet–bath interactions.