135 citations · 430 across the 9 of their papers we have counts for
9 papers
Origin of granular axial segregation bands in a rotating tumbler: An interface-mixing driven Rayleigh-Taylor instability
Umberto d'Ortona, Richard Lueptow, Nathalie Thomas
The origin of large and small particle axial bands in long rotating tumblers is a long-standing question. Using DEM simulations, we show that this axial segregation is due to a Ray…
Mechanisms for recirculation cells in granular flows in rotating cylindrical rough tumblers
Umberto d'Ortona, Nathalie Thomas, Richard Lueptow
Friction at the endwalls of partially-filled horizontal rotating tumblers induces curvature and axial drift of particle trajectories in the surface flowing layer. Here we describe…
Self-Induced Rayleigh-Taylor Instability in Segregating Dry Granular Flows
Umberto d'Ortona, Nathalie Thomas
Dry granular material flowing on rough inclines can experience a self-induced Rayleigh-Taylor (RT) instability followed by the spontaneous emergence of convection cells. For this t…
Evidence of reverse and intermediate size segregation in dry granular flows down a rough incline
Nathalie Thomas, Umberto D'ortona
In a dry granular flow, size segregation behave differently for a mixture containing a few large beads with a size ratio (S) above 5 (Thomas, Phys.Rev.E 62,96(2000)). For moderate…
Influence of Rough and Smooth Walls on Macroscale Granular Segregation Patterns
Umberto D'Ortona, Nathalie Thomas, Richard M. Lueptow
Size bidisperse granular materials in a spherical tumbler segregate into two different patterns of three bands with either small particles at the equator and large particles at the…
Influence of Rough and Smooth Walls on Macroscale Flows in Tumblers
Umberto D'Ortona, Nathalie Thomas, Zafir Zaman +1
Walls in discrete element method simulations of granular flows are sometimes modeled as a closely packed monolayer of fixed particles, resulting in a rough wall rather than a geome…