Numerical investigation on hydrodynamics of vertically confined free film

For intensification of the film transfer process, flow behaviours of a novel type of liquid film, "confined free film" (a coexistence of both wall-bounded and unbounded films), on a vertically-aligned plate with an open window were investigated using the CFD modelling approach. It was found from the simulations that the liquid flow profiles of confined free film in the region of the open window vary with flow time. The average film thickness of the confined free film in the open window region is approximately 0.50~0.67 of that in the solid wall region, while the corresponding velocity is approximately 1.7~2.0 times faster. The falling film reaches its maximum thickness value and maximum velocity magnitude at the lower part of the open-window region in the current study. Simulation results also indicated that the region of the lower-wall plate promotes both varicose and sinuous wavy behaviour of the confined free film, while the open-window region assists in exciting film wave motion in the lower-wall region. Compared with vertically falling free film, the confined free film exhibits several distinctive features in its flow behaviour.