Rheological changes of suspensions induced by electrohydrodynamic instability

A new type of ER suspension is Invented with a fluorinated organic compound . The suspensions show a viscosity increase without yield stress on the app lication of electric fields. The results cannot be explained by the chain f ormation mechanism. After the ER experiments, the plate surface of rheomete r is covered with stripes of aggregated particles. The periodic structure m ay be formed in the electrified suspensions. When a dielectric liquid is su bjected to high electric fields, the secondary motion of liquid can be indu ced. The electrohydrodynamic convection is responsible for the periodic dis tribution of particles. The ER effect of the suspensions may be generated b y a combined effect of electrohydrodynamic convection and external shear.