Preferred orientations of prolate particles in grain flow are analyzed by experiments and simulations. Experiments shows that temporal local jam and its propagation leads to form the dynamic chain structure of grains and that grains of the structure tends to lean their major axis upstream with higher imbrication angles up to 35 degrees. Simulations of particulate flow are conducted by Distinct Element Method (DEM). Prolate particles are represented by a pair of overlapping spheres. Simulation results show that intergranular stress concentrates into the chain structure. Prolate grains tend to rotate their major axis perpendicular to strong compression stress acting on the structure. This is a formation mechanism of preferred orientation.

Keywords: Distinct Element Method Simulation, Dynamic Grain Chain, Experiment, Grain Flow, Imbrication, Intergranular Stress, Multiple-Collision, Orientation, Stick-Slip Motion

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