A Novel Volume of Fluid Model for Numerical Simulation of Wettability of Falling Film over Horizontal Tubes

Wettability is a fraction of wetted area on tubes by a film flow. In this study, the wetting characteristics of falling film on the horizontal tube are numerically investigated. The wetting characteristics are dependent on the properties of the liquid and flow regime especially in droplet and droplet to jet mode. However, experimental efforts observed in the literature are based on the measurement of mass flow rate and it is difficult to record wettability of tube. The objective of this paper is to record wettability of tube using numerical simulation. A numerical study is carried out using a computational fluid dynamics (CFD) code for 3D configuration considering geometrical and thermophysical parameters using volume of fluid model in Fluent 6.0. Commonly used fluids of modified Galileo number in the range of 36 to 552 are used for numerical simulation. In the current study, correlations of wettability measurement for smooth and rough surface are introduced. The results based on the generalized proposed correlations are validated with the experimental studies. It is observed that wettability increases with mass flow rate and diameter of tube and is maximum for high viscous fluid.