A recent development in magnetic fluids research is reviewed. The research activities in this field are increasing accompanied with the success of the synthesis of magnetic fluids with excellent magnetic properties. Apparent viscosity and rheological properties are discussed in connection with the particle aggregates in the applied magnetic field. As the thermo-fluid dynamics of magnetic fluids, recent investigations on the pipe flow problems and heat transfer control are taken up. Finally, as the representative examples of recent studies on the applications of magnetic fluids, various sensors, actuators, grinding device and heat pipe are explained.
