Microstructural simulations of magnetic suspensions

The motion of nanometric or micrometric magnetic particles is modeled through a sophisticated research code, named SIMS. This code was developed by Prof. Rafael Gabler Gontijo during his PhD Thesis. SIMS uses an efficient methodology that considers: particle translational and rotational motion, hydrodynamic and magnetic interactions and Brownian motion. The code may be used to study problems in sedimentation or rheology (with simple and oscillatory shear).

The longe range interactions are accounted by a rigorous technique of Ewald sums that guarantees the convergency of the method and its ability to recover theorical and experimental predictions when calculating transport properties of magnetic suspensions. This research line is focused in linking the microstructural behavior of magnetic suspensions and the macro-rheological response of ferrofluids. In this sense we are interested in observing the parameters that change the initial random configuration of the suspension and lead to structure formation and/or breakup. We also study how the physical parameters such as the suspension polidispersity, the intensity of the applied field and particle dipole moment, the size of the particles, the carrier liquid temperature and others, influence the suspension stability. This research line is also concerned in answering some important and fundamental questions of particulate systems, such as: the influence of hydrodynamic interactions on the magnetization of ferrofluids, the convergence of particle mean variance with respect to the system size (screening) for magnetically interacting spheres, how does polidispersity changes the fluid magnetization and viscosity, how strong interparticle magnetic interaction may lead to non linear responses of ferrofluids excited with sinuisodal oscillatory shears, and so on. Bellow you may see an interesting video of chain formation due to magnetic interactions under the presence of an external field.

For more simulations performed with SIMS by Prof. Rafael Gabler Gontijo, you may consult my Youtube channel.