Dynamics of liquid film rupture under local heating

Rupture dynamics of a horizontal liquid film non-uniformly heated from below was experimentally studied in a wide range of liquid viscosity. To visualize the liquid surface deformations and disruption of the film, an optical schlieren system was used. The instantaneous local film thickness was measured using a chromatic confocal sensor. In order to measure the thickness of thin liquid films, the substrate was covered with a black coating eliminating reflection of the incident light. Angular and frequency characteristics of the confocal sensor were studied in detail. The process of film rupture can be divided into three stages: 1) film thinning down to a residual film on the heater; 2) existence of a stable residual film for some time; 3) rupture and dry out of the residual film. The thickness of the residual film was found to strongly depend on the liquid viscosity: for water it is about 10 mu m, whereas for silicone oil PMS-20 0 it is about 275 mu m. The data obtained for various working liquids were generalized by a dimensionless correlation. (c) 2021 Elsevier Ltd. All rights reserved.

Automated summary

The rupture dynamics of a horizontally heated liquid film from below were experimentally studied across a wide range of liquid viscosities. The deformations and disruption of the film were visualized using an optical schlieren system, and the local film thickness was measured using a chromatic confocal sensor. The process of film rupture was found to have three stages, and the residual film thickness strongly depended on the liquid viscosity.