| A summary of results is presented from experiments in granular systems, which are excited by vertical and/or horizontal vibrations. The transitions between different dynamic states depend on internal properties of the granular system like the density of particles and on external parameters of the driving shakers. Characteristic for granular systems are such counterintuitive phenomena as the crystallization by increasing the vibration amplitude and thereby the energy input, or the rise of large particles in a sea of smaller ones (Brazil-nut effect). For horizontal shaking of a binary system the demixing of small and large particles is found to occur at the same critical particle density as the liquid-solid transition. The combined action of both vertical and horizontal vibrations for the controlled transport of bulk solids is utilized already for a long time in industrial applications. In a certain driving range it is known that standing surface waves occur at half the forcing frequency. The three experiments presented here indicate that the four major concepts describing the complex behavior of a vibrated granular system, namely phase transition, segregation, pattern formation, and transport are closely related and yield a rewarding field for future research. |
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