Simulations of splashing micro-scale droplets on a dry surface

Speaker Name: 
Arnout Boelens
Speaker Organization: 
Stanford University
Start Time: 
Monday, April 24, 2017 - 4:00pm
End Time: 
Monday, April 24, 2017 - 5:00pm
Location: 
Engineering 2, Room 280
Organizer: 
Daniele Venturi

Abstract

Emerging printing applications require control of the impact of ink droplets on surfaces at increasingly small length scales. At atmospheric pressure and at sufficiently large velocities, a familiar splash is produced when a droplet impacts a solid dry surface. However, counterintuitively, when the ambient pressure is reduced, the droplet smoothly deposits on the surface. Due to a limited knowledge of contact-line behavior and liquid-sheet stability, the origins of this so-called ''pressure effect'' are not well understood.In this presentation the pressure effect is explored numerically by resolving the Navier-Stokes equations down to a 3-nm resolution. The simulations reproduce key experimental features and, importantly, provide new insights into length and time scales that are not easily accessible by experiments. This has allowed us to identify a previously unknown high-speed "rolling'' contact line regime. In addition, our scaling analysis suggests that there is universal physics across different splashing regimes.