Dynamic shear flow behavior of magneto-rheological fluid between two rotating parallel disks under relatively weak magnetic field

The transient shear stress variation and the flow patterns of an MR fluid have been investigated simultaneously under constant shear rate and relatively weak magnetic field using a parallel disk rotary rheometer. The effects of magnetic field, shear rate and gap height on the induced shear stress and the flow behavior of the MR fluid were evaluated. The behavior of shear stress changes remarkably and various flow patterns (cracks in packed MR fluid structure, grain-like particle's agglomeration, line of grains, etc.) with MR fluid leakage out of the gap can be observed, depending on these parameters. The amount of the MR fluid leakage due to the centrifugal force also depends on these parameters. Both the evolution of pattern and the leakage of MR fluid might be responsible for the transient variation of shear stress.