  We use mesoscale simulations to study the depinning of a receding contact
line on a superhydrophobic surface patterned by a regular array of posts. In
order that the simulations are feasible, we introduce a novel geometry where a
column of liquid dewets a capillary bounded by a superhydrophobic plane which
faces a smooth hydrophilic wall of variable contact angle. We present results
for the dependence of the depinning angle on the shape and spacing of the
posts, and discuss the form of the meniscus at depinning. We find, in agreement
with [17], that the local post concentration is a primary factor in controlling
the depinning angle, and show that the numerical results agree well with recent
experiments. We also present two examples of metastable pinned configurations
where the posts are partially wet.
