Bubble Motion and Collapse Behavior in High-Viscosity Fluids Falling Film Flow Field

Abstract

Falling film flow significantly enhances devolatilization efficiency in polymer processing, predominantly facilitated by bubble dynamics. The falling film flow characteristics of high-viscosity fluids, the bubble motion, and collapse mechanism in the falling film flow field were investigated numerically and experimentally. The result shows that increased fluid velocity markedly alters bubble morphology, hastening bubble rupture and reducing the time taken for bubbles to reach the liquid film surface. With increasing fluid viscosity, the duration for bubble motion and collapse increases, especially in high-viscosity fluids where the bubble detaches from the liquid film surface, involving growth into a bubble film, followed by rupture near its peak. When the fluid viscosity is 10 Pa·s, the distance from the bubble film peak to the liquid film surface can reach up to 8 mm. Overall, the falling film flow field can promote the removal of bubbles in high-viscosity fluids.