Flow of Nano and Micron Size Particles in a Cylindrical Cavity

Flow of particles is analyzed by considering driving force from applied shear energy (rotating augers). against constraints of extrinsic constraints (consolidation, boundary) and intrinsic constraints (cohesion, compressibility and inter-particle forces). Both Discrete Element Method (DEM) and Continuum Models are used to analyze powder flow with DEM uses models at particle level and is therefore requires costly computation where as Continuum Models are less accurate for complicated geometries and free surfaces. The cohesive (tensile) stress for an assembly of cohesive particles is an increasing function of volume fraction but depends only weakly on shear rate. As the particle volume fraction is decreased, the dependence of the tensile stress on shear rate grows, but for all volume fractions, this dependence is much weaker than that of the total stress. Empirical correlations are costly to obtain for predicting developer flow from frequent bench experiments (Freeman tester, Jenike shear cell and Seville tester) and tests in fixtures and housings. A rheological equation can be used to analyze shear stress, normal stress, cohesive stress and dynamic coefficient of friction in a shear cell. Experimental results are compared with the existing models.