Spatially resolved measurement of anisotropic granular temperature in gas-fluidized beds

This paper reports the measurement of granular temperature in gas-fluidized beds using magnetic resonance. Experiments were performed using 0.5 and 1.2 mm diameter particles (Geldarts group B and D) in both a 3-dimensional cylindrical bed and a 2-dimensional rectangular bed. Measurements were performed over a range of motion encoding times to confirm that the experiments were in the ballistic regime. The results confirm that the granular temperature arises from shear induced by the bubble motion. It was found that the hydrodynamics in the 2D and 3D geometries were significantly different with lower bubble velocities but a higher bubble temperature in the 2D bed than in the 3D bed. The granular temperature was also found to be highly anisotropic, with Tz up to 10 times greater than Tx or Ty.