Diffusion of ellipsoidal granular particles in shear flow

Abstract

The diffusion of nonspherical particles has not been well understood due to the complexity of their contact mechanics and self‐organization of their orientations. We perform discrete element method simulations of monodisperse ellipsoids in a shear flow with Lees‐Edwards boundary conditions to quantify the relation between the diffusion coefficient and the flow parameters. The results indicate that the particle aspect ratio strongly affects the diffusion coefficient by influencing the particle orientation and alignment. We develop a scaling law for the diffusion coefficient perpendicular to the flow direction, Dyy, which combines the influences of the shear rate , the solids fraction f, the effective particle diameter deff and the particle aspect ratio Z. We show that , where kd is a dimensionless pre‐factor, and a fit is obtained for the functional form of χ(f, Z). This scaling law will be useful in developing continuum transport models for applications.

Self-diffusion of spherocylindrical particles flowing under non-uniform shear rate

“…In fact, monodisperse assemblies of non-spherical particles are suitable to isolate diffusion from other mechanisms. Recently, R. Cai et al 23 numerically examined self-diffusion in a system of ellipsoids, using Lees-Edwards boundary conditions, and varying the particle aspect ratio systematically. They proposed a generalized scaling law for the diffusivity in the direction perpendicular to the flow in terms of an effective particle size d eff , the aspect ratio x and the solid fraction f, namely, D B w (f, x)_ gd eff 2 .…”

Advanced applications of cellulose nanocrystals: a mini review

“…The modelling results showed that particle aspect ratio is closely associated to particle alignments and direction at the continuous shear rate and ref. 77 . later confirmed the findings of this work.…”