An automated single-particle tracker: application to characterization of non-azimuthal motion in Couette flows at low Reynolds number

作者：Blaj O; Merzeau P; Snabre P; Pouligny B^*

来源：Experiments in Fluids, 2011, 50(6): 1559-1570.

DOI：10.1007/s00348-010-1013-y

We describe an experiment that allows us to record 3-dimensional trajectories of single particles in Couette shear flows, at low Reynolds number. The core of the apparatus is a Couette cell with transparent contra-rotating cylinders. Fluorescent spherical particles are used as tracers. A single tracer is imaged onto a webcam, equipped with a home-made autofocus system. For a given average shear rate, tracking of an individual tracer is performed automatically by driving the amount of contra-rotation between both cylinders and the position of the webcam. The performance of the tracker is illustrated through examples of trajectories of neutrally buoyant tracers in a Newtonian fluid. The setup is mostly aimed at characterizing complex flows in non-colloidal concentrated suspensions and wet granular materials. We show examples of 3d trajectories in a dense suspension of 200 mu m spherical grains, revealing details of the short-scale diffusive-like particle motion, together with flow localization and large-scale non-azimuthal flow patterns.

• 出版日期2011-6