Diffusion of ellipsoidal granular particles in shear flow

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 D-yy = k(dx) (f,Z)gamma d(2)eff, where k(d) is a dimensionless pre-factor, and a fit is obtained for the functional form of x(f, Z). This scaling law will be useful in developing continuum transport models for applications.

Automated summary

The diffusion coefficient of nonspherical particles in shear flow was studied through discrete element method simulations. It was found that the particle aspect ratio strongly affects the diffusion coefficient by influencing particle orientation and alignment. A scaling law for the diffusion coefficient perpendicular to the flow direction was developed, which will be useful in developing continuum transport models for applications.