Instability of a magnetic fluid drop in a capillary: a numerical study

Abstract

In a magnetic field longitudinal to a cylindrical capillary, a magnetic fluid drop elongates until surface instability occurs. Two different types of instabilities arise as the magnetic field intensity increases. For fluids with small contact angles, the instability is caused by the drop breakage along the capillary axis with a subsequent fluid spreading over the capillary wall. For fluids with large contact angles, the instability is due to fluid separation from the capillary wall with a formation of a freely suspended drop inside the capillary. The main objective of the present work is a numerical study of the instability phenomena under a longitudinal uniform magnetic field. The problem is considered in a wide range of contact angles