Granular layering at large particle-size ratios

In a tilted chute, red glass beads about six times wider than white beads form repeated rows separated by smaller grains. Why does this sheared mixture form layers, rather than simply sorting big grains above or below small ones?[1]

A chute experiment with two sizes of dry glass beads produces rows of large grains separated by small grains. What selects this spacing and order under shear at large size ratios? The observed pattern is finer than bulk segregation, which tracks overall relative migration of the two sizes.[1]

The layers occur in experiments and simulations. Their mechanism and the conditions that allow them remain open.[1]

Sheared simulations without gravity or rigid walls also develop layers. This supports a shear-driven effect, but leaves its mechanism and parameter range unresolved, including its prevalence with more grain sizes.[1]

An orderly pattern emerges from an initially disordered flowing mixture. It offers a test of how grain-scale motion produces larger structures.[1]

The layers alter deformation and packing in the studied flows. They test where an averaged mixture description loses essential grain-scale structure; broader practical consequences still require investigation.[1]