USE OF IMAGE PROCESSING TO STUDY AN EVAPORATING EXTENDED R113 MENISCUS

The technological importance of the processes of fluid flow and heat transfer in thin liquid films has initiated in depth theoretical and experimental studies over the years. The pioneering works of Derjaguin and his coworkers established the foundation for the study of thin film transport processes. They proposed the existence of an excess chemical potential in a thin film as a result of the solid-liquid-vapor intermolecular force field, which they defined, in units of pressure, as disjoining pressure. The predominant contribution to the disjoining pressure is the van der Waals dispersion forces. Derjaguin and Zorin studied the adsorption of alkanes on substrates at high disjoining pressures. Using the adsorption isotherm and the disjoining pressure concept, they demonstrated that thin film transport is capable of enhancing the evaporation rate from capillaries. An experimental study by Bascom et al. added significant insights to the spreading mechanisms of liquids over solid surfaces. Potash and Wayner theoretically studied the transport phenomena in an extended meniscus formed on a vertical plate. The extended meniscus consisted of an intrinsic meniscus, in which the pressure gradient for the flow results from the capillarity and a thin film region. The thin film region consisted of an evaporating thin film, in which the flow occurs as a result of a disjoining pressure gradient and an equilibrium thin adsorbed film where the superheated liquid is kept from evaporating by the solid liquid intermolecular forces. They concluded that the pressure drop resulting from a change in meniscus shape is sufficient to replenish the evaporated liquid. Wayner et al. presented a microscopic model for the heat transfer coefficient in the thin film region using the effusion equation and a pressure gradient in the liquid based only on the intermolecular forces.