Investigations of microstructured behaviors of magnetorheological suspensions

Microstructured behaviors of magnetorheological suspensions under magnetic fields with different magnitudes are investigated using a large-scale atomic/molecular massive parallel simulator. We investigated four kinds of typical characteristics of microstructured behaviors: (a) phase separation of structures, (b) statistics of chain and cluster sizes, (c) structural anisotropy of aggregates, and (d) fluctuation of suspensions. It is found that the higher the magnitude of external magnetic fields, the lesser the time the phase separation of structures undergoes. Magnetic dipolar particles, moreover, exhibit plane size-dependent structured behavior as they tend to cluster into nematic-like sheets along the shorter dimension of the field-perpendicular plane, even under conditions of uniform initial distribution and steady magnetic fields. In the presence of the shear, meanwhile, we observe that the suspensions move along with the flow field and connect to form long sheets along flow direction toward restraining the transportation of the shear flow. The application of the shear weakens the effect of the magnetic fields on the fluctuation of suspensions. Besides, the macroscale shear stress of magnetorheological suspensions is investigated as a function of the Mason number revealing that the constitutive model of rheological suspensions based on the Bingham law is of applicability.