CFD Simulation of Laminar Film Condensation on a Vertical Surface

Two-dimensional simulations of laminar film condensation on a vertical surface are presented. A modified version of the interFoam solver present in OpenFOAM was developed, in order to take into account for energy and mass transfer. The Volume of Fluid (VOF) method is used to track the vapor-liquid interface, with the effects of interfacial stress, gravity and surface tension being considered. Concerning the mass transfer model between phases, several models are used in the literature. Some authors have chosen empiric models, which incorporate some parameters that must be tuned by trial and error. The right estimate of those parameters is essential, since excessively high values lead to numerical convergence problems, while too small values cause a significant deviation between interfacial and saturation temperatures. The model used in this work forces the equilibrium state in the interface cells, in a dynamic way, which allows mesh independence to be achieved. The obtained numerical results are compared against analytical results from Nusselt theory. The present numerical model is able to reproduce satisfactorily not only the Nusselt theory predictions, but additional effects (not included in that theory), namely, inertial forces, convective terms and interfacial shear stresses