Taylor vortex flow of magnetic fluids under the influence of an azimuthal magnetic field

We have investigated the influence of an azimuthal magnetic field on the stability of Taylor-Couette flow. The stabilization of Couette flow due to the action of the magnetic field has been used to determine the rotational viscosity of the magnetic fluid as a function of the magnetic field strength, The results of the experiments are compared with theoretical calculations on rotational viscosity [1] and on Taylor-Couette flow in magnetic fluids [2]. If the size distribution of the magnetic particles is taken into account, good qualitative agreement is found. Any remaining quantitative discrepancies can be attributed to the interaction between the particles which is neglected in the theories.