Courbure de la frontière d'une zone sèche dans un film en écoulement

We study experimentally the shape of dry patches inside a film flowing along an inclined plane at relatively high value of the contact angle θ. Their radius of curvature R near apex, is given by R/l_c∼l_cV_c/(Γ sinα)−F(α,θ), where Γ is the flow rate per unit length, α the plate slope, and F(α,θ) is a correction that increases with θ and decreases with α (l_c and V_c are the capillary length and the capillary velocity). A simple model allows us to recover this correction and also the existence of a critical flow rate above which dry patches disappear.