Acceleration characteristics of dielectric particles in ER fluids

In this paper, laser speckle velocimetry is proposed to measure the acceleration of starch particles in ER fluids. It is verified that speckles can be formed by illuminating laser beam on the starch ER fluids. The speckle patterns was recorded with high speed CCD camera, and velocity and acceleration can be calculated by self-programming cross-correlation computing program. The experimental results showed the acceleration changed oscillatorily with time under certain electric field, there is a critical electric field and a critical particle concentration, when lower than this critical electric field (concentration), the mean particle acceleration increased; otherwise, it decreased. The acceleration component parallel to electric field were larger than that perpendicular to electric field. Usually, it is regarded that the movement of dielectric particles in ER fluids is related to the generation of electrorheological effect.