The dynamics of a free failing particle curtain were analysed and studied in the laboratory. In the experiments a steady, uniform, high-voidage stream of particles was fed through a rectangular slit to form a curtain across the entire width of a horizontal duct of cross-section of 0.15 x 0.60 m. The thickness of the particle stream at the inlet was varied over the range 2-10 cm by varying the width of the rectangular slit. The particle flow rates were maintained constant at approximately 0.040 kg/s. The shape of the particle curtain was recorded using a highspeed video camera. Our results indicated a low voidage curtain led to diverging curtain; increasing the initial voidage of the particle stream caused the curtain to become less divergent; further increase the voidage of the particle stream caused the curtain to become increasingly convergent. The shape of particle curtain was analysed using an Eulerian-Eulerian computational fluid dynamics (CFD) model. Reasonable agreement was found between the experiments and the CFD model predictions. (c) 2009 Elsevier B.V. All rights reserved.