Effect of particle flow dynamics on the fabric evolution in spherical granular assemblies filled under gravity
The evolution of contact anisotropy (or fabric) for a spherical granular assembly filled under gravity is investigated. The effect of filling positions and the particle inlet velocity on the contact anisotropy is presented. Discrete Element Method is used to generate the granular assemblies by filling the particles into a container under gravity. The contact anisotropy and the coordination number shows a strong dependence on the filling locations. However, when these assemblies with distinct initial anisotropy are subjected to uniaxial compression, their contact anisotropy approaches the same value. The initial velocity of the particles shows a significant effect on the contact anisotropy of the granular assembly. It was found that the contact anisotropy first decreases and then increases showing a zone of minimum anisotropy with increase in inlet particle velocity. Initiation of particle whirling motion was found as the reason for this zone of minima. The inlet particle velocity at which the minimum contact anisotropy is observed depends on the direction of the particle motion. The findings in this work will be useful in identifying the critical spots (with high heat or force) and in designing better granular beds with uniform distribution of fabric via filling.
Keywords: Contact network, Discrete element method, Fabric, Contact anisotropy, Packed granular bed,