要約

This work seeks the steady-state solution for a magnetic fluid filling a thin porous annulus between two moving cylindrical walls under the influence of a radially outward magnetic field. The cylinders were either perfectly insulated or perfectly conducting. Current results show that there will be an invariant point independent of the strength of magnetic and flow fields if both cylinders are insulated. This point may shift toward the inner cylinder as the permeability increases. When the inner cylinder is insulated while the outer one is perfectly conducting, the velocity close to the inner cylinder decreases with the strength of the external magnetic field. At the same time, a reverse flow is found close to the outer cylinder after being pushed by its local clockwise Lorentz force. When the inner cylinder is perfectly conducting and the outer cylinder is insulated, the current density surrounding the inner cylinder reduces while that next to the outer cylinder increases. This leads to a special phenomenon where the magnetic fluid actually flows faster as the strength of the external magnetic field increases.