Control of vortex breakdown in confined two-fluid flows

This paper describes the first experimental evidence of how vortex breakdown develops and disappears in both upper and lower fluids in a sealed vertical cylindrical container, where two immiscible fluids circulate driven by the rotating lid while other walls are stationary. The rotating lid generates both swirling and meridional circulations of the upper and lower fluids. The most intriguing and practically important flow phenomenon is the formation of local circulation cells (vortex breakdown). Our experimental study reveals that vortex breakdown can occur in (a) upper, (b) lower, and (c) both fluids. The kind of flow pattern depends on properties of liquids. The vortex breakdown flows can intensify heat and mass transfer.