| The ferrofluid consists of colloidal suspensions of single domain magnetic nanoparticles and base liquid. It has the magnetism of the solid magnetic material and the liquidity of the liquid, so it may be considered as a new type of liquid. The ferrofluid can be magnetized to the saturated state in presence of an external magnetic field. The magnetized ferrofluid presents different characteristics from common liquids. From the thermodynamics view, the ferrofluid has the complicated thermomagnetic characteristics and may make heat transport process controllable.The thesis applies macroscopic continuous medium model to studying the thermomagnetic convection characteristics of ferrofluids under both uniform-grads fields and non-uniform magnetic fields by numerical and experimental approaches. The main efforts are focused on flow and heat transfer characteristics of ferrofluids under the gravity and magnetic force. The flow and heat transfer model is established. Based on this model, macroscopic flow characteristics of ferrofluids in a rectangular box and between two slabs are simulated using professional software of Fluent under different temperature, magnetic field and volume fraction of particles. Also the flow and heat transfer characteristics of the ferrofluid inside a columned box is experimentally studied. The effects of temperature, magnetic fields volume fraction of particles on the thermomagnetic convection of the ferrofluid are investigated.
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