Transverse vortices induced by modulated granular shear flows of elongated particles
Abstract
We perform discrete element method (DEM) simulations of elongated grains in a shear cell for various particle aspect ratios and contact frictions, with an additional heterogeneous force perturbation in the flow direction. For a perturbation in the form of a single Fourier mode, we show that the response of the system consists of transverse secondary flows that average onto a pattern of four vortices. We also theoretically studied this phenomenon by generalizing the granular rheology to the case of elongated grains and computing the linear response to such a perturbation. Even if the agreement between theory and simulations remains qualitative only, we can reproduce and understand the inversion of the vortex pattern when the cell aspect ratio is increased from a vertically to a horizontally elongated cell shape, emphasizing the key role of the second normal stress difference as well as the cell geometry.
Cite
@article{arxiv.2502.10079,
title = {Transverse vortices induced by modulated granular shear flows of elongated particles},
author = {Sára Lévay and Philippe Claudin and Ellák Somfai and Tamás Börzsönyi},
journal= {arXiv preprint arXiv:2502.10079},
year = {2025}
}