Abstract
Electrowetting On Dielectric (EWOD) refers to a parallel-plate device
that
moves fluid droplets through electrically actuated surface tension
effects.
The fluid dynamics are modeled using HeleShaw type equations (in 2-D)
with a
focus on including the relevant boundary phenomena. Specifically, we
model
contact line pinning as an inequality constraint for the motion of the
liquid-gas interface that accounts for the "sticking" effect of the
interface. The model is presented in a variational framework and
is
discretized using Finite Elements. The curvature/surface tension
is
discretized in a semi-implicit way for accuracy using an explicit
representation of the interface. The line pinning effect is
captured with a
variational inequality (similar in spirit to the Signorini
problem). In
addition to this, we are developing a method for handling pinching and
reconnection of droplet meshes in an automatic way. Some
simulations will
be presented exhibiting the pinning effect and some preliminary results
on
topological changes.