Liquid Film Formation on a Rotating Disk (2nd Report, Numerical Analysis of the Film Thinning Process with Heat and Mass Transfer)

The unsteady flow of a liquid film and the surrounding gas on a rotating disk, which is related to a spin-coating technique to form a thin uniform film on a plate, is simulated numerically with emphasis on the heat and mass transfer at the interface. The full governing equations and boundary conditions are formulated and a newly developed calculation method is applied. The numerical results reveal that the liquid film thickness decreases mainly by convection in the middle stage. The radial and azimuthal velocities are proportional to the radius, and other values are independent of it. According to these results, one-dimensional calculation models for both phases are developed. The results show that the increased viscosity due to the evaporation of the solvent has considerable effects on the film formation process when the film is sufficiently thin. The liquid film thins mainly because of evaporation in the last stage.