Influence of the form of short-range repulsive interactions on final shape of internal structure in magneto-rheological fluids
Marek Barski
Quarterly No. 1, 2017 pages 30-36
DOI:
keywords: magneto-rheological fluids, ferromagnetic particles, computer simulation, molecular dynamics, short-range repulsive interactions, microstructure
abstract The presented paper is devoted to the task of computational simulation of ferromagnetic particles in magneto-rheological fluids. Under the action of an external magnetic field, ferromagnetic particles form a complex internal microstructure. This microstructure is generally parallel to the direction of the external magnetic field intensity vector. The main aim of this work is to investigate the influence of the short-range repulsion interactions between the particles on the final shape of the internal microstructure. This interaction is implemented in the simulation process in such a way that the moving particles do not overlap. In the adopted theoretical model, in addition to the effects of short-range repulsion interactions, magnetostatic and hydrodynamic interactions are also taken into account. It is worth stressing that the applied theoretical model is very simple, however, it enables estimation of the mentioned effect. It was assumed that all the ferromagnetic particles have a spherical shape with a constant radius. A series of two-dimensional numerical simulations is carried out based on the molecular dynamic algorithm. The short-range repulsive interactions are described by a polynomial and by an exponential function with various parameter values. It turned out that the final shape of the microstructure strongly depends on the applied form of short-range repulsion. It is possible to obtain single isolated strings of particles as well as complex structures known as particle clusters.