RHEOLOGICAL AND MICROSTRUCTURAL CHARACTERISTICS IN GRANULAR SHEAR FLOW OF 2D ELLIPTICAL PARTICLES

Abstract

This is an extension work based on our previous one [J. Xiaoyu and T. Matsushima, J. Appl. Mech., JSCE, 2018]¹⁾ in which we mainly discussed the influence of intergranular friction and particle size distributions on granular shear flow of circular particles by comparing discrete element simulation with 𝜇(I)-rheology model. In this paper, we focus on the simple shear flow of elliptical particles under various inertial numbers I and investigated the influence of particle aspect ratio 𝛼 on the flow rheology and microstructural characteristics. It was found that (1) the 𝜇(I)-rheology model is well applicable for the flows of the elliptical particles of different aspect ratio 𝛼; (2) the deviation of macroscopic friction 𝜇(I) and solid fraction 𝜙(I) from the quasi-static state, i.e., 𝜇−𝜇₀ and 𝜙₀−𝜙, are linearly correlated, and it is independent of 𝛼; (3) the logarithm of particle orientation distribution log 𝑃(𝜃) is well described by a trigonometric function with a particle orientation anisotropy 𝑎_ρ; (4) the linear relation in (2) is explained by the microscopic observation in which 𝜇−𝜇₀ and 𝜙₀−𝜙 are uniquely related to 𝑎_ρ, respectively, showing that increasing randomness of particle orientation causes both increasing 𝜇 and decreasing 𝜙.