Capturing gas and particle motion in an idealised gas-granular flow

A model two-dimensional gas-granular flow, consisting of 4.76 mm-diameter nylon beads constrained to move between two glass plates, was investigated using particle image velocimetry (PIV) to measure the gas flow, and simultaneous image analysis to measure the motion of the bed particles. PIV confirmed that the deviations from the mean gas flow in the absence of large particles followed a Gaussian distribution, and clearly showed the motion of the gas around the large particles. The gas flow between two adjacent particles was seen to increase, and particles below one another were seen to reduce the gas flow around higher particles. No dependence of the gas flow on the direction of motion of the bed particles could be discerned, and the bed particles typically had speeds of around 1/10 of the gas speed.