Figure 12. Averaged angular velocity of large particles for different blends.

4.4 Particle interactions

In addition to the large particle rotation, different particle mixtures may have different particle interactions that also contribute to the shear stress difference. The contact numbers for three contact types, i.e. the contact between large and large particles L-L, large and small particles L-S, and small and small particles S-S, are shown in Figure 13. While only L-L contacts and S-S contacts exist for monodispersed large and small particles, respectively, the number of S-S contact dominate the numbers of the other two types of contacts. The number of S-S contacts for the three binary mixtures decreases with increasing mass fraction of large particles, as a lower large particle mass fraction leads to a higher number of small particles and a higher number of S-S contacts.