Frontiers in Heat and Mass Transfer (FHMT), 4, 013002 (2013) DOI: 10.5098/hmt.v4.1.3002 Global Digital Central ISSN: 2151-8629 1 INVESTIGATION OF PARTICULAR FEATURES OF THE NUMERICAL SOLUTION OF AN EVAPORATING THIN FILM IN A CHANNEL Greg Ball, John Polansky, Tarik Kaya * Department of Mechanical and Aerospace Engineering, Carleton University, Ottawa, Ontario, K1S 5B6, Canada ABSTRACT The fluid flow and heat transfer in an evaporating extended meniscus are numerically studied. Continuity, momentum, energy equations and the Kelvin-Clapeyron model are used to develop a third order, non-linear ordinary differential equation which governs the evaporating thin film. It is shown that the numerical results strongly depend on the choice of the accommodation coefficient and Hamaker constant as well as the initial perturbations. Therefore, in the absence of experimentally verified values, the numerical solutions should be considered as qualitative at best. It is found that the numerical results produce negative liquid pressures under certain specific conditions. This result may suggest that the thin film can be in an unstable state of tension; however, this finding remains speculative without experimental validation. Although similar thin-film models proved to be very useful in gaining qualitative insight into the characteristics of evaporating thin films, the results shown in this study indicate that careful experimental investigations are needed to verify the mathematical models. Keywords: Thin film, evaporating meniscus, capillary force, disjoining pressure 1. INTRODUCTION The study of thin films is important in many technological applications, including the cooling of electronics, evaporation, condensation, boiling, drying etc. The film dynamics are governed by various complex physical mechanisms such as surface tension, disjoining pressure, thermal conduction and phase change. Because of its importance, thin films have been widely studied. The problem of modelling an evaporating thin film has been investigated by many authors using various techniques. Solutions governed by 3rd and 4th order Ordinary Differential Equations (ODE) have been proposed. In addition to the problem formulation (3rd versus 4th order), the existing models used different boundary conditions, and different techniques in the calculation of the mass transport across the interface. More recently, simulations based on the molecular dynamics were also attempted. Because of the very small length scales involved, few experimental works have been completed and majority of the models do not have the necessary validation required for providing further insight into whether the models produce accurate physical solutions. Several authors have expanded upon current works by imposing different boundary conditions and observing the corresponding effect. Table 1 provides a sample of common variations undertaken by various authors. Note that the varying thermophysical properties, refers to whether the numerical model updates the fluid properties as a function of temperature in generating a solution. Table 1 Comparison of some earlier works on modelling an evaporating meniscus. Authors Non-isothermal Interfacial Condition Varying Thermophysical Properties Slip Boundary condition Polarity Effect Superheat Effect (at least 5 K range) Potash and Wayner (1972)  - - - - Wayner et al. (1976)  - - - - Moosman and Homsy (1980)  - - - - Hallinan et al. (1994)  - - - - Park et al. (2003) - -  - - Qu et al. (2002)  - -  - Zhao et al. (2011)   - -  Wee et al. (2005)     - Wang et al. (2007)  - - -  Present Study    -  * Corresponding author. E-mail: tkaya@mae.carleton.ca. Frontiers in Heat and Mass Transfer Available at www.ThermalFluidsCentral.org