  Recent experiments by Kavousanakis et al., Langmuir, 2018 [1], showed that
reversible electrowetting on superhydrophobic surfaces can be achieved by using
a thick solid dielectric layer (e.g. tens of micrometers). It has also been
shown, through equilibrium (static) computations, that when the dielectric
layer is thick enough the electrostatic pressure is smoothly distributed along
the droplet surface, thus the irreversible Cassie to Wenzel wetting transitions
can be prevented. In the present work we perform more realistic, dynamic
simulations of the electrostatically-induced spreading on superhydrophobic
surfaces. To this end, we employ an efficient numerical scheme which enables us
to fully take into account the topography of the solid substrate. We
investigate in detail the role of the various characteristics of the substrate
(i.e. the dielectric thickness, geometry and material wettability) and present
relevant flow maps for the resulting wetting states. Through our dynamic
simulations, we identify the conditions under which it is possible to achieve
reversible electrowetting. We have found that not only the collapse
(Cassie-Baxter to Wenzel) transitions but also the contact angle hysteresis of
the substrate significantly affects the reversibility.
