2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/16582We consider the stability of a system of equations which are a singular perturbation of the incompressible rigid-plastic flow equations used to model granular flow. A linear stability analysis shows that solutions of these equations are unstable, in general, and that these instabilities may lead to ill-posedness. However, the analysis suggests that these equations are more regular, in a certain sense, than the unperturbed incompressible rigid-plastic flow equations. Numerical solutions are presented which illustrate the growth of instabilities and the development of shear-bands in the flows.21 pages, 7 figuesSoft Condensed Mattertext