Velocity profile and torque measurements

I. Title: Velocity Profile and Torque Measurements of Circular Taylor-Couette Flow in Cobalt-Ferrite Ferrofluids Subjected to Applied Magnetic Fields

II. Objectives:

In this investigation,velocity profiles and torques for Cobalt-Ferrite Ferrofluids, which are water based, will be measured under the influence of an applied magnetic field at different frequencies and amplitudes. Thefluid will be treated as a continuum. Changes in the variables (such as concentration and viscosity) that could influence the ferrofluid’s response to the applied magnetic field will be created. It is ofparticular interest to observe under which conditions spin-up flow will appear. The analysis will be carried out in a cylindrical geometry and in an annular gap.

III. Background:
Ferrofluidsare colloidal dispersions. They consist of ferromagnetic particles in a suspension. They are of great importance nowadays. For this reason, it is relevant to understand their properties and behaviorso that a wide range of applications could be obtained. Current applications of ferrofluids are the following ones: sealing rotating shafts, lubrication of machines, making of printer ink, and evenbiomedical sciences. In order to study the rheology of these fluids, different geometries could be used. One that is very common is the cylinder. The fluid, which is viscous and incompressible, is placedbetween two coaxial cylinders that are rotating. This is known as Taylor-Couette Flow. The phenomenon of spin-up flow has been studied also by placing the ferrofluid in a container of cylindricalshape and subjecting it to a rotating magnetic field. Eventually, due to the effects of this field, a velocity profile will develop for the fluid that is being studied. The frequency, amplitude anddirection of the magnetic field can be changed. Depending on how these parameters are set, the flowing direction of the ferrofluid changes. There can be one point where the fluid will rotate in the same...