Separation and Stripe Formation in Fluid-Driven Granular Mixtures.
Abstract: We shall describe an investigation of vertically vibrated and horizontally vibrated mixtures of bronze and glass spheres immersed in a viscous fluid. These systems exhibit novel behaviour, including almost complete segregation of the components and striped pattern formation. By means of computer simulation and experimentation, we have identified the under-lying separation mechanism and the relation between separation under vertical and horizontal conditions. Our simulations show very good qualitative agreement with experimental observations of pattern formation, allowing us to identify the dominant length scale. Other aspects of the experiments, including the filling-fraction of the system and the time dependence of the separation are also discussed.