Simultaneous Rayleigh-Taylor and Kelvin-Helmholtz Instabilities in Inclined Granular Chute Flows

We perform numerical computational fluid dynamics-discrete element method (CFD-DEM) simulations of binary granular mixtures in a chute flow at varying particle density ratios. We observe the formation of Kelvin-Helmholtz (KH) waves in the direction of the flow and the Rayleigh-Taylor instability (RTI) perpendicular to the flow. The RTI instability grows faster when the density ratio is increased. By fluidizing the system using upwards gas flow we mitigate the KH waves and decrease the time for the RTI to occur. We investigate the segregation index to provide control guidelines for mixing or segregating binary chute flows.