Departamento de Física

Facultad de Ciencia
Universidad de Santiago de Chile

Seminario de Física - Miércoles 6 de Diciembre - 3:30 PM - "Dynamics of drop impact on solid surfaces: evolution of impact force and self-similar spreading"

12/06/2017 - 15:30
Título: "Dynamics of drop impact on solid surfaces: evolution of impact force and self-similar spreading"
Dr. Leonardo Gordillo, académico Departamento Física
Universidad de Santiago de Chile
We investigate the dynamics of drop impacts on dry solid surfaces. By synchronising high-speed photography with fast force sensing, we simultaneously measure the temporal evolution of the shape and impact force of impacting drops over a wide range of Reynolds numbers (Re). At high Re, when inertia dominates the impact processes, we show that the early-time evolution of impact force follows a square-root scaling, quantitatively agreeing with a recent self-similar theory. This observation provides direct experimental evidence on the existence of upward propagating self-similar structures during the initial impact of liquid drops at high Re. When viscous forces gradually set in with decreasing Re, we analyse the early-time scaling of the impact force of viscous drops using a perturbation method. The analysis quantitatively matches our experiments and successfully predicts the increase of the maximum impact force with decreasing Re. Furthermore, we discuss the influence of viscoelasticity on the temporal signature of impact forces. Last but not least, we also investigate the spreading of liquid drops at high Re following the initial impact. Particularly, we find an exact parameter-free self-similar solution for the inertia- driven drop spreading, which quantitatively predicts the height of spreading drops at high Re. As such, our study provides a quantitative understanding of the temporal evolution of impact forces across the inertial, viscous and viscoelastic regimes and sheds new light on the self-similar dynamics of drop impact processes.


Miércoles 6 de Diciembre del 2017, a las 15:30 hrs.
Sala de Conferencias, 3er Piso
Departamento de Física
Universidad de Santiago de Chile

Doctorado en Ciencia con Mención en Física