Rotational motion of a dielectric particle immersed in slightly conductive dielectric liquid

Since the elongated particles have experimentally shown better ER effect than spherical ones, chain formation mechanism of suspensions was investigated by using a large scale model. In series of the experiment with this large scale model, interesting and peculiar particle motions were observed. Experimental set up consists of parallel electrodes immersed in Silicone fluid whose conductivity was changed by adding butylalcohol. The motion of propylene rod with a diameter of 0.7 mm and 6 mm long was examined by using video camera and also high-speed camera. At very low conductivity, there is no motion of the rod. When the conductivity is increased, there is many different kind of motion observed. Rotational motion was most frequently observed at a certain range of conductivity. Further increase of applied field, there is a circular motion of the rod. The rotational speed increases with the applied field. However, when the circular motion starts, the rotational speed decreases. The highest rotational speed observed was 11 rps