Continuum mechanical foundation for the flow of granular materials is established. The material is assumed to consist of cohesionless rigid spheres of uniform size and weight. Macroscopic laws are deduced from microscopic considerations of interparticle friction by means of statistical inference. The field is described by the theory of polar fluids. Various characteristics of granular materials such as the critical stress condition and the angle of repose are mathematically deduced from the theory. The effects of couple-stress in the Couette flow between two parallel plates is also studied and the ‘boundary layer’ is shown to exist.
