EXPERIMENTAL-EVIDENCE SUPPORTING KINEMATIC MODELING OF THE FLOW OF GRANULAR MEDIA IN THE ABSENCE OF AIR DRAG

Experiments have been carried out with closely graded, coarse glass ballotini of various sizes to investigate the effect of varying the mean particle diameter on the value of the kinematic constant, B. A strong linear dependence is found between the two except for the case of the smallest ballotini (≈600 μm diameter). For this material, significantly different flow patterns were obtained and this is attributed to flow retardation by the interstitial fluid medium. Based on experimental evidence, a dimensionless, empirical constant, k, is proposed to replace the kinematic constant, B, for the flow of coarse granular media in the absence of air drag. © 1979.