Yielding behavior of model magnetorheological fluids.

The yielding behavior of magnetorheological fluids is revisited through the use of finite element method calculations on model structures and carefully conducted experiments in a magnetorheometer. Model structures investigated in this work are monoclinic lattices with simple and body centered bases. From the simulation point of view we emphasize the influence of the interparticle gap separation. From the experimental point of view we elucidate the importance of the magnetic field application and the occurrence of slip at the confining surfaces. Simulations demonstrate that the yield stress τ0 scales with the interparticle center-to-center distance h as τ0/M2 ∝ h-6 where M is the particle magnetization. A good agreement is found when the simulated yield stresses are compared with the experimental ones, independent of the particular packing and interparticle gap.