Competition of roller rotation and horizontal crossflow to control the free surface cusp-induced air entrainment
Santosh Kumar Panda, Basanta Kumar Rana, Parmod Kumar
Abstract
Efforts are made to delineate the dynamics of entrained gaseous cusps and flow of liquid films wrapped around a horizontal partially submerged rotating roller numerically. The solid roller is allowed to rotate across the gas–liquid interface with a fixed submergence ratio of 0.5 (equally immersed in both gaseous and liquid phases) and the gaseous phase is subjected to horizontal crossflow. The finite volume-based solver Gerris has been employed to track the interfacial configuration by using the volume of fluid (VOF) method. The combined influence of roller rotation (ω) and strength of crossflow (Reflow) on the wrapped film thickness and the structure of entrained cusp is demonstrated thoroughly for different gas–liquid pairs in order to understand the underlying physics. This study also includes the transient dynamics of liquid tip movement from the receding to advancing junction for various Reflow and gas–liquid pairs. Subsequently, the structure and rate of entrainment are also estimated, where the collapsible gaseous jet breaks into circular gaseous bubbles. Predictions are also made in order to establish the dependence of interfacial configuration on the Archimedes number (Ar). Finally, a theoretical model has been developed to elucidate both entrainment and wrapped film dynamics, which shows excellent agreement with the numerical results.