STRUCTURAL AND RHEOLOGICAL STUDY OF MAGNETIC FLUIDS USING MOLECULAR DYNAMICS

In this study, molecular dynamics simulations based on a magnetic dipole theory were developed to study microstructural evolution, rheological properties and potential ener-gies of magnetic fluids (MF) under steady shear or compression. In general, the magnetic interaction dipole forces drive the nanoparticles to form firstly a chain-like and then a column-like structure under an externally applied magnetic field. The potential energies are time-dependent and the static yield stresses increase with the growth of magnetic field strength. Under the steady shear, the one-dimensional chain or column structures would transform into lamellar patterns. The shear stresses were theoretically predicted and they agreed well with experimental results. Under compression, when magnetic flu-ids were compressed along the magnetic field, simulation results show that the materials exhibit enhanced yield stresses and the work of compressive loading is absorbed mostly by the repulsive potential energy. Introduction. Magnetic fluids [1], a kind of colloidal suspension of magnetic nanoparticles, have attracted considerable interests due to their wide applications, such as magnetorheological technology, storage technology [2], biomedicine [3], etc