Friction coefficient of rod-like chains of spheres at very low Reynolds numbers. I. Experiment
نویسندگان
چکیده
We present a new method to measure hydrodynamic friction forces on colloidal particles at very low (ci 10~~) Reynolds numbers with high accuracy. Exploiting magnetic field induced aggregation of microcopic paramagnetic spheres into straight chains of calibrated length, we determine the anisotropic friction coefficient of the chains, with a range from one to 100 particles, by video-microscopic observation of sedimentation speed. The results are found to agree well with the Slender-body theory, even for small chain lengths. The effects of the proximity of a wall are also explored. There are various analytical and numerical solutions of the Stokes
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