Dynamic electrorheological effects and interparticle force between a pair of rotating spheres

We consider a two-particle system in which a particle is held fixed, and th e other one rotates around the axis perpendicular to the line joining the p articles' centers. The rotating particle leads to a displacement of its pol arization charge on the surface. Our results show that the rotational motio n of the particles generally reduces the force between the particles. The d ependence of interparticle force on the angular velocity of rotation will b e discussed.