چكيده به لاتين
Magnetorheological fluid is a type of smart fluids, which can rapidly be changed from a liquid state to a solid state, by application of a magnetic field. This greately changing in rheological properties of MR fluid, is due to the dipolar interactions between magnetized particles, which induce their aggregations to form chain-like structures aligned with the external magnetic field. In recent studies, particle-level simulation of MR fluids has been a very interesting object, with consideration of more accurate methods, which take into account fundamental phenomena in flow of MR fluids, i.e particle dynamics, magnetic forces and base fluid hydrodynamics. One of these simulation approaches is DEM-CFD coupling method, which has been used in this work, with consideration of magnetic interactions. The flow of base fluid was simulated using the Lattice Boltzmann Method (LBM), as the CFD technic, and dynamic of suspended particles in MR fluid was calculated using the Discrete Element Method (DEM). Furthuremore, dipolar interactions between magnetized particles, were modeled by implementation of the fixed dipole model, into LAMMPS, and all simulations were carried out using these software packages, for a MR fluid of containing about 15 percent volume fraction of suspended carbonyl iron in silicone oil, under shear loading. The shear rate was varied from about 30 to 1000 s-1, in the presence of magnetic field strengths of 36, 73 and 109 kA/m. For the first time, DEM-LBM coupling method were used to simulate MR fluid with prediction of its rheological properties for a wide range of shear rates and magnetic fields. The simulations were performed in two stages, particle chains formation and different shear loading conditions for MR fluid. A stronger magnetic field at the first stage, results in only shorter response time, and the final chain configuration were not very different, for example a total duration of 30 ms were achieved for the magnetic field strength, 73 kA/m. At the second stage rheological results were in good agreement with experimental data, and a total error of 15.51 were achieved. Furthuremore, a sheet like structure of MR particles was seen at high shear rates depending on the mafnetic field intensity.
