Flow of granular materials has been a subject of numerous investigations in the past few decades. A number of experimental techniques have been used in these studies. Examples include PEPT (Positron Emission Particle Tracking), NMR (Nuclear Magnetic Resonance), HSP (High-Speed Photography), and various tomographic methods. These techniques have been used to study a number of model systems such as rotating drums, chute flows, vibro-beds, hopper flows, fluidised beds, and shear cells, in order to gain an insight into the behaviour of granular flows. In this paper, a brief review of these experimental techniques and model systems will be made first. Attention will then be paid to the work on rotating drums and fluidised beds using the non-invasive PEPT technique. Finally, future directions of the experimental aspects of shearing granular materials will be discussed.
