Material property effects on granular flow through orifices

A relationship was developed to predict the flow resistance of granular materials as a function of the minimum length of the particle dimensions and surface roughness, eliminating the need for costly field calibration. The resistance term was found to be a linear function of the minimum particle dimension. The slope for the relationship was independent of surface roughness; however, the intercept varied with surface roughness. Without considering surface roughness effects on the intercept, the linear relationship predicted measured resistances with an R² = 0.85. With the materials grouped into two types, smooth and rough, and individual intercept values determined for each group, the R² values increased to 0.99 and 0.98 for Type I (smooth) and Type II (rough) materials, respectively.