Experimental study of a horizontal shear-driven liquid film approaching a sharp corner. Critical conditions.

The present work concerns the experimental study of a horizontal liquid film (order of 1-2mm thickness) driven by an external turbulent air flow on a flat plate of low surface energy and its separation due to the presence of a convex sharp corner. The liquid film is formed free on the plate without side wall borders, which would restrict the expansion towards the spanwise direction. Although the slow dependency on time reported during the characterization of the film, the critical conditions, which is the main objective of this study, remain unaffected. The measurements showed that the critical conditions are independent on the variations of the width of the film and depend only on the local film velocity and thickness at the corner. An empirical equation has been proposed to describe the onset of film atomization at the corner. A first attempt to compare the experimental data with models documented in literature shows that further theoretical development is required.