video: Brownian particles under oscillatory shear. The top panel shows the global shear motion the researchers applied. The bottom panel shows the motion of particles under shear. The size of particles (black dots) is 1 micrometer. Two kinds of motions can be clearly identified in the bottom panel: one is the global collective motion of particles under shear, consistent with the shear motion shown in the top panel; the other is the random Brownian motion of each particle, seen as small random zig-zag movements of particles. The competition between these two motions gives rise to the interesting shear thinning and viscoelastic effect, as shown in the paper. This image relates to an article that appeared in the Sept. 2, 2011, issue of Science, published by AAAS. The study, by Dr. Xiang Cheng of Cornell University in Ithaca, N.Y., and colleagues was titled, "Imaging the Microscopic Structure of Shear Thinning and Thickening Colloidal Suspensions.” view more
Credit: Video courtesy of Xiang Cheng