Ferrofluid appendages: Ferrofluid vortex container - A numerical investigation of free surface shape and vortex flow in ferrofluids for different relative densities

Abstract

Abstract. The use of ferro uids as shapeable external appendage to a submerged body and as a mean of vortex ow induction is studied in this paper. Ansys-CFX numerical results are validated against analytical problems and used to analyze the ferro uid free surface shape a ected by gravity, di erent magnets, and di erent densities of the surrounding non-magnetic uids. It is demonstrated that the height, width, and curvature of ferro uid can be controlled by magnet size and strength. It is also observed that ferro uid mass loss may occur due to gravity, which should be addressed in designing a uid appendage. Subsequently, vortex production inside the ferro uid is investigated via a shear ow on the magnet. It is shown that ferro uid can contain complex vortices while being shaped by the magnetic eld, gravity, and the vortices. It is also observed that vortices inside the ferro uid a ect the ow of the surrounding uid. Additionally, the e ects of surface tension and viscosity are brie y analyzed to roughly show the importance of these parameters for further works. Overall, it is concluded that using ferro uids as appendages for shaping and controlling uid ow around submerged bodies seems to be practical and calls for more attention.