Aggregation kinetics of carbonyl iron based magnetic suspensions in 2D.

We investigate the (irreversible) two-dimensional aggregation kinetics of dilute non-Brownian magnetic suspensions in rectangular microchannels using video-microscopy, image analysis and particle-level dynamics simulations. Special emphasis is given to carbonyl iron suspensions that are of interest in the formulation of magnetorheological fluids. The results are compared to non-Brownian suspensions of magnetic latexes. We demonstrate that both suspensions follow a deterministic aggregation process. Furthermore, experimental and simulation aggregation curves can be collapsed onto a master curve when using the appropriate scaling time (∝λ-1 ϕ2D -2.5 ) as a function of only two dimensionless numbers: the lambda ratio (λ) and the particle surface fraction (ϕ2D ).