Entrainment of air driven by rotational field inside viscous liquids

Abstract

Here, we propose an intelligent method for entrainment of air inside viscous liquids using submerged rotational mechanisms. A cylindrical disc is immersed inside liquid with its axis transverse to the nominal interfacial plane and rotated at wide range of rotational Reynolds number (4.88 - 14.64). This configuration is simulated using grid based volume of fluid technique in air-polybutene pair. A dip in nominal interface profile is observed at low disc rotations however, gradual progress of rotational inertia has resulted in elongation of interface in the form of a filament of air progressing inside liquid. Transient progress of entrainment depicts pointed curvature like cusped singularities in its profile during the early stages. When this cusp like entrainment gets into the high inertial zone, it grows in radial direction, along with its downward growth due to the centrifugal effect of the surrounding liquid. The interplay of inertia and viscous resistance is also controlled by the initial submergence of the rotating disc along with its rotational inertia. The outcome of the present study could be utilized for the design of chemical reactors, mixing processes and devices relating transfer process as working principle.