A quantitative study of enhanced drying flux from a narrow liquid-air interface of colloidal suspensions during directional drying

We evaluate an enhancement of the drying flux from a narrow drying interface. We examine drying of colloidal suspensions in a directional drying cell with various combinations of width and height to change the area of the drying interface. The drying flux changes depending on the height or width of the drying interface. A simple scaling law describes the experimental data quantitatively. Using this effect, we systematically change the drying flux and analyze the formation kinetics of particulate films. There is a threshold drying flux for immediate film formation after the beginning of drying. In addition, the threshold drying flux depends on the initial volume fraction of particles. A kinetics model based on the conservation of particles explains the threshold well.