Dynamics and rheological properties of suspensions of paramagnetic spherical particles under constant magnetic fields

Magnetorheological fluids span an astounding range of applications. Investigating such systems provides insight into the relationships between the rheological properties and the imposed flow and magnetic conditions, thus aiding in the processing of the magnetorheo-logical fluids. In this study, we apply an in-house Stokesian dynamics code to investigate the dynamics, microstructures, and rheological properties of magnetorheological fluids under constant magnetic fields with different directions and magnitudes. A spectral Ewald method is applied to improve the computational capability. Constrained two-dimensional and fully three-dimensional simulations are conducted, and the results are compared. A magnetic-thickening phenomenon is observed in both the constrained two-dimensional and fully three-dimensional simulations, when the magnetic field is in the shear-flow-gradient direction. However, a magnetic-thickening phenomenon is observed in the constrained two-dimensional simulation while a magnetic-thinning phenomenon is observed in the fully three-dimensional simulation when the field is in the shear-flow direction.