Figure 11. Time-lapse images of large particle rotation with two seconds between images In order to verify this hypothesis, the angular velocities of the large particles in the various mixtures are examined via DEM simulations. Figure 12 shows the averaged angular velocity of the large particles for different blends. It is clearly found that the averaged angular velocity for monodispersed large particles is significantly higher than those of binary mixtures, demonstrating that the addition of smaller, more cohesive particles reduces the average angular velocity of the large particles. This reduction in angular velocity, making particle shearing more difficult, consequently leads to an increase in the shear stress of the binary particle mixture. While this reduced angular velocity will give rise to an increased binary shear stress, it is believed that the shear stress distribution of the binary mixture is a combined results of many factors including, but not limited to, the rotation of the larger particles. Therefore, the effect of particle interactions on the shear stress is further explored.