Structure evolution of electrorheological fluids under flow conditions

Transparent electrode with a conducting film on a glass surface provides us a useful tool to observe the fired-induced structure formation in ER fluid s directly under both quiescent and dynamic conditions. In this paper the f low and field-induced structure evolution in ER fluids will be studied in t hree flow conditions, i.e., (a) ER fluids flowing through a slit channel be tween two fixed parallel transparent electrodes, which construct a model ER valve, (b) ER fluids being sheared between two concentric transparent elec trode tubes, which correspond to a conventional rotary rheometer and (c) ER fluids being sheared between two parallel plate disks, which correspond to an ER clutch. Shear-induced layer structure was observed even when the she ar rate reaches 600 s(-1). A tentative phase transition diagram between the layer structure and the homogeneous now state will be given.