Bending and growth of entrained air filament under converging and asymmetric rotational fields

Abstract

Here we have proposed the increase of the entrainment rate by extruding an air filament under the action of convergent but asymmetric rotational field. By varying the source speed and the diameter of rotational fields, we showed the bending of an air filament towards the higher strength direction of the asymmetric inertia. Interfacial profiles like bubble ejection from the air filament and non-collapsible entrainment with air accumulation in a stagnant zone are obtained in finite volume based numerical simulations, on gradual increase of average rotational fields. Physical understanding of bent interface profile reveals the presence of multiple stages in filament growth depending upon the inertia of surrounding medium. Accumulation of air in the stagnant zone is found to be more prominent in case of rotational speed based asymmetry in contrast to its counterpart having diametric asymmetry of imposing sources. Relative comparison between these two methods of producing asymmetric field showed faster growth of filament upon varying the source diameter, while keeping the speed same. In case of extreme retardation and enhancement of rotational asymmetry, film pinch off and formation of bubble train have been reported. The shape of ejected bubbles is governed by the inertia of the surrounding medium, and bubbles have taken elliptical shapes with their major axis aligned parallel to the adjacent velocity field.