Angular plane curtain coating by drawdown of extruded polymer

An approximate analytic solution for an angular plane curtain coating of a highly viscous Newtonian fluid is developed. We obtain expressions for the melt curtain shape, coating thickness, contact length, contact pressure, dr awing force, apparent contact angle, and contact convexity. Specially const ructed examples enable practitioners to apply the results without advanced training in fluid mechanics. We identify a process indeterminacy that arise s in curtain coating employing a parallel slit. We show that, with a rapidl y converging extrusion slit, this indeterminacy vanishes. Thus, a unique so lution for the contact length is always obtained. The extension to a viscoe lastic fluid is also briefly considered.