Drop impact onto a moving substrate: Aerodynamic rebound

The dynamics of droplets approaching fast moving surfaces of high surface-tangential velocities is relevant to
numerous technical applications, such as icing phenomena in aviation. Due to the substrate motion a boundary
layer is formed which interacts with impacting droplets. In the present study, the transition from drop impact
and splashing to boundary layer induced drop rebound is investigated for varying drop diameters, drop and
plate velocity, as well as impact angles. It is found that this transition is strongly influenced by the degree
of drop deformation that is induced by aerodynamic forces acting on the drop when it enters the boundary
layer. Based on these considerations, a threshold model is obtained that describes the transition from splash
to aerodynamic rebound. It is shown that the model is valid for a laminar and a turbulent boundary layer
agreeing well with own and existing experimental data.