The splitting of thin liquid films. Kinematics

Abstract

The kinematics of film splitting have been explored inside a role nip using a disc and cone apparatus especially developed for the purpose. High-speed photographs and cinematographs have been made of the action in the nip. Two regimes of flow have been discerned. At slow speeds, fluids have time to flow counter to the roll direction into the region of low pressure where separation begins. At high speeds, cavitation or bubble formation occurs in the low-pressure region. The number of bubbles formed has been counted as a function of speed, nip pressure, and film thickness: they increase with increases in the first and third of these variables, and decrease slightly with increase in the second. Pigmentation increases the number of bubbles formed. These cavitation studies have shed light on the mechanisms of film splitting and fluid transfer.