Role of crossflow and immersion ratio on interfacial flow when swirling drum sinks partly: A computational study

The present work numerically investigates the role of crossflow and immersion ratio on the interfacial configurations when a cylindrical drum sinks partially within a bath. Film coating and fluid entrainment are the most imperative findings of this computational study, which are significantly relevant to industrial operations like coating on papers, metal sheets, and fabrics, and mixing techniques like marine hydrodynamics, atmospheric layer mixing, ocean thermocline, food processing, etc. Several dimensionless relevant input quantities such as Capillary number (Ca), Reynolds number (Reflow), immersion ratio (S/D), Morton number (Mo), and Archimedes number (Ar) are involved to anticipate the new findings. First, the critical immersion ratio, S/Dcritical is anticipated to demarcate the air and liquid coating drum. S/Dcritical monotonically increases as Reflow grows continually for a fixed Ca. We have determined steady azimuthal length of the liquid crest βl−s* and vertical shift of the leading front of the liquid cusp Yl−s* when the drum is surrounded by gaseous phase at steady state condition. Simultaneously, film thickness h*, cusp width H*, and cusp length θs* are analyzed meticulously when the drum is surrounded by liquid phase. A thicker liquid encapsulates the drum for a higher S/D compared to a lower S/D at a fixed Reflow. Importantly, the pattern of θs* drops consistently against Reflow for a constant magnitude of S/D and Ca. Velocity vectors are used to predict the fluidic behavior and highlight important physics. The role of gravitational pull and viscous drag is delineated using Archimedes number (Ar) and Morton number (Mo), respectively. Finally, an analytical solution has been developed to predict the film and cusp width under steady state conditions in the presence of crossflow for different values of Ca and S/D. A satisfactory agreement is predicted between computational and analytical approaches.