Experimental Investigation of a Contact Line Dynamic Induced by Liquid Evaporation Heat and Mass Transfer

The aim of the present study is to propose an original method to compute the shape of the interface in the vicinity of a contact line after a film break. The principle of the experiment consists in a controlled volume of evaporating liquid (HFE7100) deposited in a millimetric cylindrical vertical well. During the evaporation process, the liquid-gas interface takes a toroidal shape delimiting an axisymmetric film with the well bottom and side walls. At the beginning, the evaporation process occurs without triple line on the bottom. Then a circular triple line appears on the bottom. The meniscus interface shape and the triple line location are instantaneously measured by laser sheet sounding from underneath and numerical inversion: This technique analyses the variation of the light intensity along a laser sheet due to its refraction trough consecutive interfaces (solid-liquid-vapor).The laser sheet impacts intensity on a perpendicular screen is inverted. The inversion result is the shape of the interface and the position of the triple line during the evaporation process.