Particle Interactions – In a fundamental analysis of the friction generated in pneumatic conveying it naturally comes down to what the particles are doing between themselves and in their impacts with the wall of the pipe. These questions were first addressed by Louge et al. (1989) who looked at impacts of large particles to gain some insight into how to model and
quantify these interactions. Borzone and Klinzing (1990) have shown that the condition of the wall surface can intimately affect the particle impact behavior. One can note in Figure 7 below the unique impact and reflection angles can occur when the surface roughness is varied. In more recent work Vasquez et al. (2008) showed the unusual behavior of flexible particles and their interactions with the wall and themselves. These particles produce considerable rotation as well as unique interactions with the wall even bouncing backward against the main flow stream. The cartoon of this behavior is seen in Figure 8. Are these