Dynamics of a bouncing drop near a solid surface

In the present work we focus on a single bouncing event of a drop on a solid surface. The dynamics of drop depends on three important non-dimensional numbers namely Reynolds number (Re = ρ_l UR_o/µ_l), Weber number (We = ρ_lU² R_{o /}σ) and Capillary number (Ca = µ_g U/σ; based on gas viscosity). To facilitate bouncing, we set We ≤ 1 and contact angle, θ = 170^o . In this We range, surface tension effects dominate over inertia and leads to complete rebound.

2D and axisymmetric simulations have been carried out using the open source code Gerris which solves incompressible Navier-Stokes equations along with an accurate interface tracking scheme (VOF/PLIC). Two different kinds of drop bouncing events have been observed. At high Re, drop makes contact with the surface and dissipates some of its energy during its interaction with the surface and hence this is a wettability-dependent event. Dynamics of this event will be discussed in detail during the meeting. At low Re, drop is supported on a gas cushion and makes no contact with the surface. This is a wettability-independent event. A detailed characterization of energetics of both these events will be presented at the meeting.