Function Of Relative Ratio Research Articles

We study the magnetorheological properties and structural transitions in novel aqueous colloidal suspensions of magnetic nanoparticles developed for biomedical applications. Defined-shape field-tunable superparamagnetic nanoparticles with clustered cores and their suspensions are produced. The region of intermediate magnetic coupling strength between colloidal ferrofluids and magnetorheological suspensions is systematically studied for the first time. Hybrid numerical simulations with hydrodynamic interactions provide full structural information. The distinctive features of the rheograms are related to transitions between Brownian and persistent microstructure, shape anisotropy, confinement and formation of magnetically coupled gel as a function of relative ratio between thermal, magnetic and hydrodynamic stresses. Non-trivial yielding scenario is observed via the shear banded (delaminated) phase, which may be more widespread in magnetic suspensions than previously thought. Analysis in terms of dimensionless parameters shows generalized behavior, which is applicable to a broad class of magnetic colloids and suspensions.

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