Figure 9. Comparison of the τpre from experiments and DEM simulations.
In order to compare the experimental packing density with the DEM predictions, the experimental packing density is converted to solid fraction. Solid fraction is calculated by dividing the packing density with the true density of the glass beads, i.e. 2500 kg/m3. The variation of solid fraction with composition is shown in Figure 10. The solid fraction in both the experiment and DEM simulations is calculated by recording the position of the top boundary under the same 2000 Pa pre-shear load. For both sizes of monodispersed spherical beads, the predicted and measured solid fraction is similar with a value around 0.6. In addition, the solids fraction for the binary mix is higher than that of the monodispersed particles, similar to what was observed by Vallejo12. The DEM predictions of solid fraction are able to reproduce the experimental measurements quite well.