ESPCI web site
Satish Kumar (University of Minnesota)
Droplet dynamics near topographical features
While solid substrates are often idealized as being perfectly smooth, all real
surfaces possess some level of topographical and chemical heterogeneity. This heterogeneity
can greatly influence droplet dynamics, and is of tremendous relevance for
applications ranging from oil recovery to water harvesting to advanced manufacturing.
In this talk, we will show how mathematical models based on lubrication theory
that account for surface topography provide insight into how
topographical features induce pinning of the three-phase contact line where
the liquid, air, and solid all meet. Sufficiently strong external forces cause
contact-line depinning, and in some cases the depinning force can be
understood through relatively simple scaling relationships. Three examples will be presented
involving (i) shear-induced depinning, (ii) gravity-induced depinning, and
(iii) evaporation-induced depinning. Comparisons to existing experimental observations
will be discussed.