Steady Flow Around a Circular Cylinder Coated with a Magnetic Fluid Film

抄録

An analysis is first presented to clarify the effects of a magnetic fluid film coated on a current-carrying cylinder on the free-stream structure and on the hydrodynamic drag force. The calculation is made for the case of Reynolds number Re=10 and a ratio between the mean film thickness and cylinder radius, ε=0.1, using a perturbation method taking ε as a parameter. Then, the effects of Reynolds number and film thickness on the film profile are experimentally studied. It is clearly shown that the drag of a cylinder is reduced by the presence of a magnetic fluid coating only when the ratio of the apparent viscosity of magnetic fluid to the viscosity of the outer fluid is less than 1/4.