A meniscus instability for the separation of a thin liquid film between parallel circular plates. 1st report. Experiment on growth of disturbances.

Abstract

In this paper, the behavior of the meniscus between two circular parallel plates in negative squeeze motion is theoretically and experimentally investigated. According to the previous study on two tilted rectangular plates, a local capillary number for circular liquid film is newly introduced and the theoretical relation between the local capillary number and the nondimensional wave number of disturbance agrees well the experimental one. It is however found that the nondimensional wave number of the experiments deviates from the theory in the case of high viscous liquid. The growth process of disturbances into fingers is precisely investigated by measuring the tip curvature of the fingers. The simple relationship between the ratio of the curvature to the thickness of the liquid and that of the curvature to the position of the tip can be found experimentally.