Numerical Investigation Of Momentum And Heat Transfer Of Magnetic Fluid

The momentum and heat transfer of magnetic fluid were studied. FVM (finite volume method) and FEM (finite element method) were used to discrete partial differential equation. With the combination of experimental method and numerical simulation, macrodynamics and heat transfer were investigated.(1) The expansion ratio was investigated in this part. The streamline pattern changed from symmetric to asymmetric as Raynolds number increased. The "elimination of vortexes" was also studied under the application of external magnetic field.(2) The expansion-contraction model was simulated later based on expansion model in (1), results of which showed that the flow pattern remained symmetrical under low Raynolds number. As Raynolds number increased, the asymmetric phenomenon and bifurcation appeared successively. The external magnetic field was also applied to make the vortexes disappeared.(3) The model of an expansion with a cylinder was investigated. The fluid flowing across the sudden expansion and around cylinder was comprehensively considered. Results showed that the flow pattern was stable under high Raynolds number with the introduction of magnetic field.(4) Nano-strontium hexaferrite (SrFe12O19) particles were prepared by co-precipitation method, using strontium nitrate (Sr(NO3)2), ferric chloride (FeCl3·6H2O), sodium hydroxide and several surfactants as starting materials. The optimum preparation conditions were obtained by TEM, XRD and VSM analysis.(5) The prepared strontium hexaferrite nano-particles were dispersed in water and then placed in hyperthermia apparatus. The temperature rise effect was investigated by changing the apparent current. Results showed that aqueous with low solid content had remarkable heating effect. (6) Numerical method was applied to investigate the temperature distribution of hyperthermia. 2 dimensional (2-D) model was established and the bioheat transfer equation was used for calculation. Different conditions such as magnetic field strength, AC frequency, particle size and solid content were considered.