Pressure Response of ER Fluids between Two Parallel-Plate Electrodes

The frequency response of the pressure drop of the ER fluids between two parallel-plate electrodes to sine-wave changes in the applied electric field is investigated for constant flow rates. The electrodes gap is set at 2mm. The ER fluids used in the present study consist of cellulose suspended in silicone oil. Unipolar and bipolar sinusoidal electric fields, and constant ones are used. The frequency of the electric fields is changed from 0.1 to 1000Hz. The averages and the amplitudes of the pressure drop are measured. Dependence of the pressure drop on electrical excitation frequency is investigated. Furthermore the microscopic behavior of ER suspension structure between two fixed electrodes is visualized for the flowing ER fluids with high speed video camera under application of the electric fields. The effect of electrical change on the pressure drop is discussed from the results of the flow visualization.