Kinematics and shear-induced alignment in confined granular flows of elongated particles

Abstract The kinematics and the shear-induced alignment of elongated particles in confined, heterogeneous flow conditions are investigated experimentally. Experiments conducted an annular shear cell with a rotating bottom wall top permitting confinement flow. Flow particle orientation statistics computed by tracking using optical imaging. Translational velocity profiles show exponential decay, surprisingly, only slip at is influenced shape. Rotations highly frustrated shape, more showing, on average, lower angular velocity. In addition, clear shear-rate dependency proneness to rotate observed, stronger inhibition low zones. average does not correspond main direction, they slightly tilted downwards. corresponding angle decreases particles’ elongation. Orientational order was observed increase elongation, surprisingly affected applied confinement. A weak but systematic decrease orientational regions higher rate. At particle-scale, fluctuations strong correlation local orientation, being strongly misaligned preferential faster. This becomes for particles, while almost unaffected