Gustav Amberg
Linne FLOW Centre
KTH
Stockholm
Capillarity and dynamic wetting phenomena are increasingly important in microfluidic applications, where very small liquid volumes need to be transported, mixed and analyzed. In many materials processes capillarity, also in the sense of surface tension at a liquid surface, is the driving force. In nature phenomena where wetting and capillarity are crucial abound, for example on the feet of insects on water, liquid repellent surfaces on plants, etc. The Cahn-Hilliard equations, coupled with the Navier-Stokes equations for fluid flow provide a good description of many such cases. In this talk, examples of such flows will be investigated using numerical simulations. Examples to be discussed are: The impact of a small solid body on a liquid surface will be strongly influenced by the dynamic wetting and the capillary forces acting on the body, and may or may not penetrate the surface or stay afloat. In microfluidics, droplet creation and handling is a key ability. We have explored numerically the conditions for splitting a droplet at a channel bifurcation. Capillary driven reacting flows in materials processing may also be discussed briefly.