  The Cassie-Baxter state droplet has many local energy minima on the textured
surface, while the amount of the energy barrier between them can be affected by
the gravity. When the droplet cannot find any local energy minimum point on the
surface, the droplet starts to slide. Based on the Laplace pressure equation,
the shape of a two-dimensional Cassie-Baxter droplet on a textured surface is
predicted. Then the stability of the droplet is examined by considering the
interference between the liquid and the surface microstructure as well as
analyzing the free energy change upon the de-pinning. Afterward, the
theoretical analysis is validated against the line-tension based front tracking
method simulation (LTM), that seamlessly captures the attachment and detachment
between the liquid and the substrate. We answer to the open debates on the
sliding research field: (i) Whether the sliding initiates with the front end
slip or the rear end slip, and (ii) whether the advancing and receding contact
angles measured on the horizontal surface are comparable with the front and
rear contact angle of the droplet at the onset of sliding. Additionally, a new
droplet translation mechanism promoted by cycle of condensation and evaporation
is suggested.
