This paper examines two-dimensional liquid curtains ejected from a narrow horizontal outlet at an angle to the vertical. Curtains are characterised by the Froude number Fr=U/ (gH) ^1/2, Reynolds number Re=UH/ and Weber number We= U^2H/, where U is the ejection velocity, g the gravity, H the outlet’s half-width, the kinematic viscosity and the surface tension. It is assumed that Fr 1 (so that the radius of the curtain’s curvature due to gravity exceeds H), Re 1 (viscosity is strong) and We 1 (surface tension is on par with inertia). It is shown that steady oblique curtains exist only subject to a constraint of the form We f (Fr^2Re), which is more restrictive than the previously known constraint We 1. Thus, sufficiently strong viscosity and/or surface tension eliminate the steady regime and make the curtain evolve – typically, rotate around the outlet, eventually producing the teapot effect.
E.S. Benilov (Mon,) studied this question.