Triple line depinning criteria of planar and axisymmetric drops.

Precise quantitative criteria predicting triple lines depinning are scarce. In order to find the, we have studied planar and axisymmetric layers and drops pinned at a sharp edges with apparent contact angle θ₀. Equilibrium is compatible with a fan of angles θ₀ bracketed by the equilibrium contact angles of the both flanks of the edge, so the triple line could remain pinned as long as θ₀ is within this fan. We find, however, critical depinning advancing θ_0a and receding θ_0r contact angles, which occur as subcritical saddle-node bifurcations with no equilibrium solutions beyond a critical suitably defined Bond number.