Mechanism of Free Surface Vortex (FSV) Formation in the Presence of Free Streamflow of Air

This study reports a computational analysis of the mechanism of free surface vortex (FSV) formation and air entrainment induced by a spinning disc in the presence of horizontal crossflow of the gaseous phase. The genesis of FSV is characterized by varying the submersion height (H/D), strength of crossflow (Ref), and rotational flux (Fr). A detailed investigation is conducted on the temporal evolution and steady characteristics of FSV using both qualitative and quantitative approaches. The configuration of FSV is noticed to be bulkier as the strength of crossflow increases for a constant rotation speed (Fr) and submersion height (H/D). Furthermore, the vortex deflects more with respect to the longitudinal axis of the disc as Ref increases for a fixed Fr and H/D. Thus, the increasing gradient maximum deflection (Xmax) against Fr is observed to be steeper at higher Ref in comparison to a lower Ref. A scattered regime map is developed to distinguish three critical interfacial configurations of FSV. Again, the configurations of FSV are characterized by considering the role of gravitational (described by Bond number, Bo) and viscous forces (specified by Morton number, Mo). A bulky FSV is observed at a lower value Bo, whereas the FSV configuration progressively thins down as the magnitude of Bo increases. Crossflow deflects the trailing junction more effectively at a lower Mo than at a higher Mo.